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<?php
/**
 * File Storage engine for cache. Filestorage is the slowest cache storage
 * to read and write. However, it is good for servers that don't have other storage
 * engine available, or have content which is not performance sensitive.
 *
 * You can configure a FileEngine cache, using Cache::config()
 *
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link          http://cakephp.org CakePHP(tm) Project
 * @since         CakePHP(tm) v 1.2.0.4933
 * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 */

/**
 * File Storage engine for cache. Filestorage is the slowest cache storage
 * to read and write. However, it is good for servers that don't have other storage
 * engine available, or have content which is not performance sensitive.
 *
 * You can configure a FileEngine cache, using Cache::config()
 *
 * @package       Cake.Cache.Engine
 */
class FileEngine extends CacheEngine {

/**
 * Instance of SplFileObject class
 *
 * @var File
 */
        protected $_File = null;

/**
 * Settings
 *
 * - path = absolute path to cache directory, default => CACHE
 * - prefix = string prefix for filename, default => cake_
 * - lock = enable file locking on write, default => true
 * - serialize = serialize the data, default => true
 *
 * @var array
 * @see CacheEngine::__defaults
 */
        public $settings = array();

/**
 * True unless FileEngine::__active(); fails
 *
 * @var boolean
 */
        protected $_init = true;

/**
 * Initialize the Cache Engine
 *
 * Called automatically by the cache frontend
 * To reinitialize the settings call Cache::engine('EngineName', [optional] settings = array());
 *
 * @param array $settings array of setting for the engine
 * @return boolean True if the engine has been successfully initialized, false if not
 */
        public function init($settings = array()) {
                $settings += array(
                        'engine' => 'File',
                        'path' => CACHE,
                        'prefix' => 'cake_',
                        'lock' => true,
                        'serialize' => true,
                        'isWindows' => false,
                        'mask' => 0664
                );
                parent::init($settings);

                if (DS === '\\') {
                        $this->settings['isWindows'] = true;
                }
                if (substr($this->settings['path'], -1) !== DS) {
                        $this->settings['path'] .= DS;
                }
                if (!empty($this->_groupPrefix)) {
                        $this->_groupPrefix = str_replace('_', DS, $this->_groupPrefix);
                }
                return $this->_active();
        }

/**
 * Garbage collection. Permanently remove all expired and deleted data
 *
 * @param integer $expires [optional] An expires timestamp, invalidating all data before.
 * @return boolean True if garbage collection was successful, false on failure
 */
        public function gc($expires = null) {
                return $this->clear(true);
        }

/**
 * Write data for key into cache
 *
 * @param string $key Identifier for the data
 * @param mixed $data Data to be cached
 * @param integer $duration How long to cache the data, in seconds
 * @return boolean True if the data was successfully cached, false on failure
 */
        public function write($key, $data, $duration) {
                if ($data === '' || !$this->_init) {
                        return false;
                }

                if ($this->_setKey($key, true) === false) {
                        return false;
                }

                $lineBreak = "\n";

                if ($this->settings['isWindows']) {
                        $lineBreak = "\r\n";
                }

                if (!empty($this->settings['serialize'])) {
                        if ($this->settings['isWindows']) {
                                $data = str_replace('\\', '\\\\\\\\', serialize($data));
                        } else {
                                $data = serialize($data);
                        }
                }

                $expires = time() + $duration;
                $contents = $expires . $lineBreak . $data . $lineBreak;

                if ($this->settings['lock']) {
                        $this->_File->flock(LOCK_EX);
                }

                $this->_File->rewind();
                $success = $this->_File->ftruncate(0) && $this->_File->fwrite($contents) && $this->_File->fflush();

                if ($this->settings['lock']) {
                        $this->_File->flock(LOCK_UN);
                }

                return $success;
        }

/**
 * Read a key from the cache
 *
 * @param string $key Identifier for the data
 * @return mixed The cached data, or false if the data doesn't exist, has expired, or if there was an error fetching it
 */
        public function read($key) {
                if (!$this->_init || $this->_setKey($key) === false) {
                        return false;
                }

                if ($this->settings['lock']) {
                        $this->_File->flock(LOCK_SH);
                }

                $this->_File->rewind();
                $time = time();
                $cachetime = intval($this->_File->current());

                if ($cachetime !== false && ($cachetime < $time || ($time + $this->settings['duration']) < $cachetime)) {
                        if ($this->settings['lock']) {
                                $this->_File->flock(LOCK_UN);
                        }
                        return false;
                }

                $data = '';
                $this->_File->next();
                while ($this->_File->valid()) {
                        $data .= $this->_File->current();
                        $this->_File->next();
                }

                if ($this->settings['lock']) {
                        $this->_File->flock(LOCK_UN);
                }

                $data = trim($data);

                if ($data !== '' && !empty($this->settings['serialize'])) {
                        if ($this->settings['isWindows']) {
                                $data = str_replace('\\\\\\\\', '\\', $data);
                        }
                        $data = unserialize((string)$data);
                }
                return $data;
        }

/**
 * Delete a key from the cache
 *
 * @param string $key Identifier for the data
 * @return boolean True if the value was successfully deleted, false if it didn't exist or couldn't be removed
 */
        public function delete($key) {
                if ($this->_setKey($key) === false || !$this->_init) {
                        return false;
                }
                $path = $this->_File->getRealPath();
                $this->_File = null;

                //@codingStandardsIgnoreStart
                return @unlink($path);
                //@codingStandardsIgnoreEnd
        }

/**
 * Delete all values from the cache
 *
 * @param boolean $check Optional - only delete expired cache items
 * @return boolean True if the cache was successfully cleared, false otherwise
 */
        public function clear($check) {
                if (!$this->_init) {
                        return false;
                }
                $this->_File = null;

                $threshold = $now = false;
                if ($check) {
                        $now = time();
                        $threshold = $now - $this->settings['duration'];
                }

                $this->_clearDirectory($this->settings['path'], $now, $threshold);

                $directory = new RecursiveDirectoryIterator($this->settings['path']);
                $contents = new RecursiveIteratorIterator($directory, RecursiveIteratorIterator::SELF_FIRST);
                $cleared = array();
                foreach ($contents as $path) {
                        if ($path->isFile()) {
                                continue;
                        }

                        $path = $path->getRealPath() . DS;
                        if (!in_array($path, $cleared)) {
                                $this->_clearDirectory($path, $now, $threshold);
                                $cleared[] = $path;
                        }
                }
                return true;
        }

/**
 * Used to clear a directory of matching files.
 *
 * @param string $path The path to search.
 * @param integer $now The current timestamp
 * @param integer $threshold Any file not modified after this value will be deleted.
 * @return void
 */
        protected function _clearDirectory($path, $now, $threshold) {
                $prefixLength = strlen($this->settings['prefix']);

                if (!is_dir($path)) {
                        return;
                }

                $dir = dir($path);
                while (($entry = $dir->read()) !== false) {
                        if (substr($entry, 0, $prefixLength) !== $this->settings['prefix']) {
                                continue;
                        }
                        $filePath = $path . $entry;
                        if (!file_exists($filePath) || is_dir($filePath)) {
                                continue;
                        }
                        $file = new SplFileObject($path . $entry, 'r');

                        if ($threshold) {
                                $mtime = $file->getMTime();

                                if ($mtime > $threshold) {
                                        continue;
                                }
                                $expires = (int)$file->current();

                                if ($expires > $now) {
                                        continue;
                                }
                        }
                        if ($file->isFile()) {
                                $filePath = $file->getRealPath();
                                $file = null;

                                //@codingStandardsIgnoreStart
                                @unlink($filePath);
                                //@codingStandardsIgnoreEnd
                        }
                }
        }

/**
 * Not implemented
 *
 * @param string $key
 * @param integer $offset
 * @return void
 * @throws CacheException
 */
        public function decrement($key, $offset = 1) {
                throw new CacheException(__d('cake_dev', 'Files cannot be atomically decremented.'));
        }

/**
 * Not implemented
 *
 * @param string $key
 * @param integer $offset
 * @return void
 * @throws CacheException
 */
        public function increment($key, $offset = 1) {
                throw new CacheException(__d('cake_dev', 'Files cannot be atomically incremented.'));
        }

/**
 * Sets the current cache key this class is managing, and creates a writable SplFileObject
 * for the cache file the key is referring to.
 *
 * @param string $key The key
 * @param boolean $createKey Whether the key should be created if it doesn't exists, or not
 * @return boolean true if the cache key could be set, false otherwise
 */
        protected function _setKey($key, $createKey = false) {
                $groups = null;
                if (!empty($this->_groupPrefix)) {
                        $groups = vsprintf($this->_groupPrefix, $this->groups());
                }
                $dir = $this->settings['path'] . $groups;

                if (!is_dir($dir)) {
                        mkdir($dir, 0775, true);
                }
                $path = new SplFileInfo($dir . $key);

                if (!$createKey && !$path->isFile()) {
                        return false;
                }
                if (empty($this->_File) || $this->_File->getBaseName() !== $key) {
                        $exists = file_exists($path->getPathname());
                        try {
                                $this->_File = $path->openFile('c+');
                        } catch (Exception $e) {
                                trigger_error($e->getMessage(), E_USER_WARNING);
                                return false;
                        }
                        unset($path);

                        if (!$exists && !chmod($this->_File->getPathname(), (int)$this->settings['mask'])) {
                                trigger_error(__d(
                                        'cake_dev', 'Could not apply permission mask "%s" on cache file "%s"',
                                        array($this->_File->getPathname(), $this->settings['mask'])), E_USER_WARNING);
                        }
                }
                return true;
        }

/**
 * Determine is cache directory is writable
 *
 * @return boolean
 */
        protected function _active() {
                $dir = new SplFileInfo($this->settings['path']);
                if (Configure::read('debug')) {
                        $path = $dir->getPathname();
                        if (!is_dir($path)) {
                                mkdir($path, 0775, true);
                        }
                }
                if ($this->_init && !($dir->isDir() && $dir->isWritable())) {
                        $this->_init = false;
                        trigger_error(__d('cake_dev', '%s is not writable', $this->settings['path']), E_USER_WARNING);
                        return false;
                }
                return true;
        }

/**
 * Generates a safe key for use with cache engine storage engines.
 *
 * @param string $key the key passed over
 * @return mixed string $key or false
 */
        public function key($key) {
                if (empty($key)) {
                        return false;
                }

                $key = Inflector::underscore(str_replace(array(DS, '/', '.', '<', '>', '?', ':', '|', '*', '"'), '_', strval($key)));
                return $key;
        }

/**
 * Recursively deletes all files under any directory named as $group
 *
 * @return boolean success
 */
        public function clearGroup($group) {
                $this->_File = null;
                $directoryIterator = new RecursiveDirectoryIterator($this->settings['path']);
                $contents = new RecursiveIteratorIterator($directoryIterator, RecursiveIteratorIterator::CHILD_FIRST);
                foreach ($contents as $object) {
                        $containsGroup = strpos($object->getPathName(), DS . $group . DS) !== false;
                        $hasPrefix = true;
                        if (strlen($this->settings['prefix']) !== 0) {
                                $hasPrefix = strpos($object->getBaseName(), $this->settings['prefix']) === 0;
                        }
                        if ($object->isFile() && $containsGroup && $hasPrefix) {
                                $path = $object->getPathName();
                                $object = null;
                                //@codingStandardsIgnoreStart
                                @unlink($path);
                                //@codingStandardsIgnoreEnd
                        }
                }
                return true;
        }
}