<?php
// +----------------------------------------------------------------------+
// | PEAR :: Cache                                                        |
// +----------------------------------------------------------------------+
// | Copyright (c) 1997-2003 The PHP Group                                |
// +----------------------------------------------------------------------+
// | This source file is subject to version 2.0 of the PHP license,       |
// | that is bundled with this package in the file LICENSE, and is        |
// | available at through the world-wide-web at                           |
// | http://www.php.net/license/2_02.txt.                                 |
// | If you did not receive a copy of the PHP license and are unable to   |
// | obtain it through the world-wide-web, please send a note to          |
// | license@php.net so we can mail you a copy immediately.               |
// +----------------------------------------------------------------------+
// | Authors: Ulf Wendel <ulf.wendel@phpdoc.de>                           |
// |          Sebastian Bergmann <sb@sebastian-bergmann.de>               |
// +----------------------------------------------------------------------+
//
// $Id: file.php,v 1.17 2005/02/18 10:21:16 dufuz Exp $

require_once 'Cache/Container.php';

/**
* Stores cache contents in a file.
*
* @author   Ulf Wendel  <ulf.wendel@phpdoc.de>
* @version  $Id: file.php,v 1.17 2005/02/18 10:21:16 dufuz Exp $
*/
class Cache_Container_file extends Cache_Container
{

    /**
    * File locking
    *
    * With file container, it's possible, that you get corrupted
    * data-entries under bad circumstances. The file locking must
    * improve this problem but it's experimental stuff. So the
    * default value is false. But it seems to give good results
    *
    * @var boolean
    */
    var $fileLocking = false;

    /**
    * Directory where to put the cache files.
    *
    * @var  string  Make sure to add a trailing slash
    */
    var $cache_dir = '';

    /**
    * Filename prefix for cache files.
    *
    * You can use the filename prefix to implement a "domain" based cache or just
    * to give the files a more descriptive name. The word "domain" is borroed from
    * a user authentification system. One user id (cached dataset with the ID x)
    * may exists in different domains (different filename prefix). You might want
    * to use this to have different cache values for a production, development and
    * quality assurance system. If you want the production cache not to be influenced
    * by the quality assurance activities, use different filename prefixes for them.
    *
    * I personally don't think that you'll never need this, but 640kb happend to be
    * not enough, so... you know what I mean. If you find a useful application of the
    * feature please update this inline doc.
    *
    * @var  string
    */
    var $filename_prefix = '';
    
    
    /**
    * List of cache entries, used within a gc run
    * 
    * @var array
    */
    var $entries;
    
    /**
    * Total number of bytes required by all cache entries, used within a gc run.
    * 
    * @var  int
    */
    var $total_size = 0;


    /**
    * Max Line Length of userdata
    *
    * If set to 0, it will take the default 
    * ( 1024 in php 4.2, unlimited in php 4.3)
    * see http://ch.php.net/manual/en/function.fgets.php
    * for details
    *
    * @var int
    */
    var $max_userdata_linelength = 257;

    /**
    * Creates the cache directory if neccessary
    *
    * @param    array   Config options: ["cache_dir" => ..., "filename_prefix" => ...]
    */
     function Cache_Container_file($options = '')
     {
        if (is_array($options)) {
            $this->setOptions($options, array_merge($this->allowed_options, array('cache_dir', 'filename_prefix', 'max_userdata_linelength')));
        }
        clearstatcache();
        if ($this->cache_dir) {
            // make relative paths absolute for use in deconstructor.
            // it looks like the deconstructor has problems with relative paths
            if (OS_UNIX && '/' != $this->cache_dir{0}  )
                $this->cache_dir = realpath( getcwd() . '/' . $this->cache_dir) . '/';

            // check if a trailing slash is in cache_dir
            if ($this->cache_dir{strlen($this->cache_dir)-1} != DIRECTORY_SEPARATOR)
                 $this->cache_dir .= '/';

            if  (!file_exists($this->cache_dir) || !is_dir($this->cache_dir))
                mkdir($this->cache_dir, 0755);
        }
        $this->entries = array();
        $this->group_dirs = array();
                    
    } // end func contructor

    function fetch($id, $group)
    {
        $file = $this->getFilename($id, $group);
        if (PEAR::isError($file)) {
            return $file;
        }

        if (!file_exists($file)) {
            return array(null, null, null);
        }
        // retrive the content
        if (!($fh = @fopen($file, 'rb'))) {
            return new Cache_Error("Can't access cache file '$file'. Check access rights and path.", __FILE__, __LINE__);
        }
        // File locking (shared lock)
        if ($this->fileLocking) {
            flock($fh, LOCK_SH);
        }
        // file format:
        // 1st line: expiration date
        // 2nd line: user data
        // 3rd+ lines: cache data
        $expire = trim(fgets($fh, 12));
        if ($this->max_userdata_linelength == 0 ) {
            $userdata = trim(fgets($fh));
        } else {
            $userdata = trim(fgets($fh, $this->max_userdata_linelength));
        }
        $cachedata = $this->decode(fread($fh, filesize($file)));

        // Unlocking
        if ($this->fileLocking) {
            flock($fh, LOCK_UN);
        }
        fclose($fh);

        // last usage date used by the gc - maxlifetime
        // touch without second param produced stupid entries...
        touch($file,time());
        clearstatcache();

        return array($expire, $cachedata, $userdata);
    } // end func fetch

    /**
    * Stores a dataset.
    *
    * WARNING: If you supply userdata it must not contain any linebreaks,
    * otherwise it will break the filestructure.
    */
    function save($id, $cachedata, $expires, $group, $userdata)
    {
        $this->flushPreload($id, $group);

        $file = $this->getFilename($id, $group);
        if (!($fh = @fopen($file, 'wb'))) {
            return new Cache_Error("Can't access '$file' to store cache data. Check access rights and path.", __FILE__, __LINE__);
        }

        // File locking (exclusive lock)
        if ($this->fileLocking) {
            flock($fh, LOCK_EX);
        }
        // file format:
        // 1st line: expiration date
        // 2nd line: user data
        // 3rd+ lines: cache data
        $expires = $this->getExpiresAbsolute($expires);
        fwrite($fh, $expires . "\n");
        fwrite($fh, $userdata . "\n");
        fwrite($fh, $this->encode($cachedata));

        // File unlocking
        if ($this->fileLocking) {
            flock($fh, LOCK_UN);
        }
        fclose($fh);

        // I'm not sure if we need this
	// i don't think we need this (chregu)
        // touch($file);

        return true;
    } // end func save

    function remove($id, $group)
    {
        $this->flushPreload($id, $group);

        $file = $this->getFilename($id, $group);
        if (PEAR::isError($file)) {
            return $file;
        }

        if (file_exists($file)) {
            $ok = unlink($file);
            clearstatcache();

            return $ok;
        }

        return false;
    } // end func remove

    function flush($group)
    {
        $this->flushPreload();
        $dir = ($group) ? $this->cache_dir . $group . '/' : $this->cache_dir;

        $num_removed = $this->deleteDir($dir);
        unset($this->group_dirs[$group]);
        clearstatcache();

        return $num_removed;
    } // end func flush

    function idExists($id, $group)
    {
        return file_exists($this->getFilename($id, $group));
    } // end func idExists

    /**
    * Deletes all expired files.
    *
    * Garbage collection for files is a rather "expensive", "long time"
    * operation. All files in the cache directory have to be examined which
    * means that they must be opened for reading, the expiration date has to be
    * read from them and if neccessary they have to be unlinked (removed).
    * If you have a user comment for a good default gc probability please add it to
    * to the inline docs.
    *
    * @param    integer Maximum lifetime in seconds of an no longer used/touched entry
    * @throws   Cache_Error
    */
    function garbageCollection($maxlifetime)
    {
        $this->flushPreload();
        clearstatcache();

        $ok = $this->doGarbageCollection($maxlifetime, $this->cache_dir);

        // check the space used by the cache entries        
        if ($this->total_size > $this->highwater) {
        
            krsort($this->entries);
            reset($this->entries);
            
            while ($this->total_size > $this->lowwater && list($lastmod, $entry) = each($this->entries)) {
                if (@unlink($entry['file'])) {
                    $this->total_size -= $entry['size'];
                } else {
                    new CacheError("Can't delete {$entry['file']}. Check the permissions.");
                }
            }
            
        }
        
        $this->entries = array();
        $this->total_size = 0;
        
        return $ok;
    } // end func garbageCollection
    
    /**
    * Does the recursive gc procedure, protected.
    *
    * @param    integer Maximum lifetime in seconds of an no longer used/touched entry
    * @param    string  directory to examine - don't sets this parameter, it's used for a
    *                   recursive function call!
    * @throws   Cache_Error
    */
    function doGarbageCollection($maxlifetime, $dir)
    {
        if (!is_writable($dir) || !is_readable($dir) || !($dh = opendir($dir))) {
            return new Cache_Error("Can't remove directory '$dir'. Check permissions and path.", __FILE__, __LINE__);
        }

        while ($file = readdir($dh)) {
            if ('.' == $file || '..' == $file)
                continue;

            $file = $dir . $file;
            if (is_dir($file)) {
                $this->doGarbageCollection($maxlifetime,$file . '/');
                continue;
            }

            // skip trouble makers but inform the user
            if (!($fh = @fopen($file, 'rb'))) {
                new Cache_Error("Can't access cache file '$file', skipping it. Check permissions and path.", __FILE__, __LINE__);
                continue;
            }

            $expire = fgets($fh, 11);
            fclose($fh);
            $lastused = filemtime($file);
            
            $this->entries[$lastused] = array('file' => $file, 'size' => filesize($file));
            $this->total_size += filesize($file);
            
            // remove if expired
            if (( ($expire && $expire <= time()) || ($lastused <= (time() - $maxlifetime)) ) && !unlink($file)) {
                new Cache_Error("Can't unlink cache file '$file', skipping. Check permissions and path.", __FILE__, __LINE__);
            }
        }

        closedir($dh);

        // flush the disk state cache
        clearstatcache();

    } // end func doGarbageCollection

    /**
    * Returns the filename for the specified id.
    *
    * @param    string  dataset ID
    * @param    string  cache group
    * @return   string  full filename with the path
    * @access   public
    */
    function getFilename($id, $group)
    {
        if (isset($this->group_dirs[$group])) {
            return $this->group_dirs[$group] . $this->filename_prefix . $id;
        }

        $dir = $this->cache_dir . $group . '/';
        if (is_writeable($this->cache_dir)) {
            if (!file_exists($dir)) {
                mkdir($dir, 0755);
                clearstatcache();
            }
        } else {
            return new Cache_Error("Can't make directory '$dir'. Check permissions and path.", __FILE__, __LINE__);
        }
        $this->group_dirs[$group] = $dir;

        return $dir . $this->filename_prefix . $id;
    } // end func getFilename

    /**
    * Deletes a directory and all files in it.
    *
    * @param    string  directory
    * @return   integer number of removed files
    * @throws   Cache_Error
    */
    function deleteDir($dir)
    {
        if (!is_writable($dir) || !is_readable($dir) || !($dh = opendir($dir))) {
            return new Cache_Error("Can't remove directory '$dir'. Check permissions and path.", __FILE__, __LINE__);
        }

        $num_removed = 0;

        while (false !== $file = readdir($dh)) {
            if ('.' == $file || '..' == $file)
                continue;

            $file = $dir . $file;
            if (is_dir($file)) {
                $file .= '/';
                $num = $this->deleteDir($file . '/');
                if (is_int($num))
                    $num_removed += $num;
            } else {
                if (unlink($file))
                    $num_removed++;
            }
        }
        // according to php-manual the following is needed for windows installations.
        closedir($dh);
        unset( $dh);
        if ($dir != $this->cache_dir) {  //delete the sub-dir entries  itself also, but not the cache-dir.
            rmDir($dir);
            $num_removed++;
        }

        return $num_removed;
    } // end func deleteDir
    
} // end class file
?>
