Merge pull request #11303 from owncloud/addFilelockToConfig

Add flock to config

2 files changed, 89 insertions, 83 deletions

diff --git a/lib/private/config.php b/lib/private/config.php
index 82a1c46c9d5..7bf3863e2a6 100644
--- a/lib/private/config.php
+++ b/lib/private/config.php
@@ -1,37 +1,12 @@
 <?php
 /**
- * ownCloud
- *
  * @author Frank Karlitschek
  * @author Jakob Sack
  * @copyright 2012 Frank Karlitschek frank@owncloud.org
  *
- * 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/>.
- *
- */
-/*
- *
- * An example of config.php
- *
- * <?php
- * $CONFIG = array(
- *     "database" => "mysql",
- *     "firstrun" => false,
- *     "pi" => 3.14
- * );
- * ?>
- *
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
  */
 
 namespace OC;
@@ -41,26 +16,45 @@ namespace OC;
  * configuration file of ownCloud.
  */
 class Config {
-	// associative array key => value
+	/** @var array Associative array ($key => $value) */
 	protected $cache = array();
-
+	/** @var string */
 	protected $configDir;
-	protected $configFilename;
-
+	/** @var string */
+	protected $configFilePath;
+	/** @var string */
+	protected $configFileName;
+	/** @var bool */
 	protected $debugMode;
 
 	/**
-	 * @param string $configDir path to the config dir, needs to end with '/'
+	 * @param string $configDir Path to the config dir, needs to end with '/'
+	 * @param string $fileName (Optional) Name of the config file. Defaults to config.php
 	 */
-	public function __construct($configDir) {
+	public function __construct($configDir, $fileName = 'config.php') {
 		$this->configDir = $configDir;
-		$this->configFilename = $this->configDir.'config.php';
+		$this->configFilePath = $this->configDir.$fileName;
+		$this->configFileName = $fileName;
 		$this->readData();
-		$this->setDebugMode(defined('DEBUG') && DEBUG);
+		$this->debugMode = (defined('DEBUG') && DEBUG);
+	}
+
+	/**
+	 * Enables or disables the debug mode
+	 * @param bool $state True to enable, false to disable
+	 */
+	public function setDebugMode($state) {
+		$this->debugMode = $state;
+		$this->writeData();
+		$this->cache;
 	}
 
-	public function setDebugMode($enable) {
-		$this->debugMode = $enable;
+	/**
+	 * Returns whether the debug mode is enabled or disabled
+	 * @return bool True when enabled, false otherwise
+	 */
+	public function isDebugMode() {
+		return $this->debugMode;
 	}
 
 	/**
@@ -128,27 +122,43 @@ class Config {
 	 * Loads the config file
 	 *
 	 * Reads the config file and saves it to the cache
+	 *
+	 * @throws \Exception If no lock could be acquired or the config file has not been found
 	 */
 	private function readData() {
-		// Default config
-		$configFiles = array($this->configFilename);
-		// Add all files in the config dir ending with config.php
-		$extra = glob($this->configDir.'*.config.php');
+		// Default config should always get loaded
+		$configFiles = array($this->configFilePath);
+
+		// Add all files in the config dir ending with the same file name
+		$extra = glob($this->configDir.'*.'.$this->configFileName);
 		if (is_array($extra)) {
 			natsort($extra);
 			$configFiles = array_merge($configFiles, $extra);
 		}
+
 		// Include file and merge config
 		foreach ($configFiles as $file) {
-			if (!file_exists($file)) {
+			if(!@touch($file) && $file === $this->configFilePath) {
+				// Writing to the main config might not be possible, e.g. if the wrong
+				// permissions are set (likely on a new installation)
 				continue;
 			}
+			$filePointer = fopen($file, 'r');
+
+			// Try to acquire a file lock
+			if(!flock($filePointer, LOCK_SH)) {
+				throw new \Exception(sprintf('Could not acquire a shared lock on the config file %s', $file));
+			}
+
 			unset($CONFIG);
-			// ignore errors on include, this can happen when doing a fresh install
-			@include $file;
-			if (isset($CONFIG) && is_array($CONFIG)) {
+			include $file;
+			if(isset($CONFIG) && is_array($CONFIG)) {
 				$this->cache = array_merge($this->cache, $CONFIG);
 			}
+
+			// Close the file pointer and release the lock
+			flock($filePointer, LOCK_UN);
+			fclose($filePointer);
 		}
 	}
 
@@ -157,6 +167,8 @@ class Config {
 	 *
 	 * Saves the config to the config file.
 	 *
+	 * @throws HintException If the config file cannot be written to
+	 * @throws \Exception If no file lock can be acquired
 	 */
 	private function writeData() {
 		// Create a php file ...
@@ -168,18 +180,34 @@ class Config {
 		$content .= var_export($this->cache, true);
 		$content .= ";\n";
 
-		// Write the file
-		$result = @file_put_contents($this->configFilename, $content);
-		if (!$result) {
-			$defaults = new \OC_Defaults;
+		touch ($this->configFilePath);
+		$filePointer = fopen($this->configFilePath, 'r+');
+
+		// Prevent others not to read the config
+		chmod($this->configFilePath, 0640);
+
+		// File does not exist, this can happen when doing a fresh install
+		if(!is_resource ($filePointer)) {
 			$url = \OC_Helper::linkToDocs('admin-dir_permissions');
 			throw new HintException(
 				"Can't write into config directory!",
 				'This can usually be fixed by '
-					.'<a href="' . $url . '" target="_blank">giving the webserver write access to the config directory</a>.');
+				.'<a href="' . $url . '" target="_blank">giving the webserver write access to the config directory</a>.');
 		}
-		// Prevent others not to read the config
-		@chmod($this->configFilename, 0640);
+
+		// Try to acquire a file lock
+		if(!flock($filePointer, LOCK_EX)) {
+			throw new \Exception(sprintf('Could not acquire an exclusive lock on the config file %s', $this->configFilePath));
+		}
+
+		// Write the config and release the lock
+		ftruncate ($filePointer, 0);
+		fwrite($filePointer, $content);
+		fflush($filePointer);
+		flock($filePointer, LOCK_UN);
+		fclose($filePointer);
+
+		// Clear the opcode cache
 		\OC_Util::clearOpcodeCache();
 	}
 }
diff --git a/lib/private/legacy/config.php b/lib/private/legacy/config.php
index 4d6fefc4e17..13ff0dbe040 100644
--- a/lib/private/legacy/config.php
+++ b/lib/private/legacy/config.php
@@ -6,32 +6,9 @@
  * @author Jakob Sack
  * @copyright 2012 Frank Karlitschek frank@owncloud.org
  *
- * 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/>.
- *
- */
-/*
- *
- * An example of config.php
- *
- * <?php
- * $CONFIG = array(
- *     "database" => "mysql",
- *     "firstrun" => false,
- *     "pi" => 3.14
- * );
- * ?>
- *
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
  */
 
 /**
@@ -42,11 +19,13 @@
  */
 class OC_Config {
 
-	/**
-	 * @var \OC\Config
-	 */
+	/** @var \OC\Config */
 	public static $object;
 
+	/**
+	 * Returns the config instance
+	 * @return \OC\Config
+	 */
 	public static function getObject() {
 		return self::$object;
 	}
@@ -92,7 +71,6 @@ class OC_Config {
 	 * @param string $key key
 	 *
 	 * This function removes a key from the config.php.
-	 *
 	 */
 	public static function deleteKey($key) {
 		self::$object->deleteKey($key);