Multistore Magento / File Owner Cache Problem

gistfile1.php

<?php
/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@magentocommerce.com so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magentocommerce.com for more information.
 *
 * @category    Mage
 * @package     Mage_Core
 * @copyright   Copyright (c) 2011 Magento Inc. (http://www.magentocommerce.com)
 * @license     http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */

/**
 * Configuration options storage and logic
 *
 * @category   Mage
 * @package    Mage_Core
 * @author      Magento Core Team <core@magentocommerce.com>
 */
class Mage_Core_Model_Config_Options extends Varien_Object
{
    /**
     * Var directory
     *
     * @var string
     */
    const VAR_DIRECTORY = 'var';
    /**
     * Flag cache for existing or already created directories
     *
     * @var array
     */
    protected $_dirExists = array();

    /**
     * Initialize default values of the options
     */
    protected function _construct()
    {
        $appRoot= Mage::getRoot();
        $root   = dirname($appRoot);

        $this->_data['app_dir']     = $appRoot;
        $this->_data['base_dir']    = $root;
        $this->_data['code_dir']    = $appRoot.DS.'code';
        $this->_data['design_dir']  = $appRoot.DS.'design';
        $this->_data['etc_dir']     = $appRoot.DS.'etc';
        $this->_data['lib_dir']     = $root.DS.'lib';
        $this->_data['locale_dir']  = $appRoot.DS.'locale';
        $this->_data['media_dir']   = $root.DS.'media';
        $this->_data['skin_dir']    = $root.DS.'skin';
        $this->_data['var_dir']     = $this->getVarDir();
        $this->_data['tmp_dir']     = $this->_data['var_dir'].DS.'tmp';
        // changed loe BOF
        //$this->_data['cache_dir']   = $this->_data['var_dir'].DS.'cache';
        $this->_data['cache_dir']   = $this->_data['var_dir'].DS.'cache'.$this->getStoreName();
        // changed loe EOF
        $this->_data['log_dir']     = $this->_data['var_dir'].DS.'log';
        $this->_data['session_dir'] = $this->_data['var_dir'].DS.'session';
        $this->_data['upload_dir']  = $this->_data['media_dir'].DS.'upload';
        $this->_data['export_dir']  = $this->_data['var_dir'].DS.'export';
    }

    public function getDir($type)
    {
        $method = 'get'.ucwords($type).'Dir';
        $dir = $this->$method();
        if (!$dir) {
            throw Mage::exception('Mage_Core', 'Invalid dir type requested: '.$type);
        }
        return $dir;
    }

    public function getAppDir()
    {
        //return $this->getDataSetDefault('app_dir', Mage::getRoot());
        return $this->_data['app_dir'];
    }

    public function getBaseDir()
    {
        //return $this->getDataSetDefault('base_dir', dirname($this->getAppDir()));
        return $this->_data['base_dir'];
    }

    public function getCodeDir()
    {
        //return $this->getDataSetDefault('code_dir', $this->getAppDir().DS.'code');
        return $this->_data['code_dir'];
    }

    public function getDesignDir()
    {
        //return $this->getDataSetDefault('design_dir', $this->getAppDir().DS.'design');
        return $this->_data['design_dir'];
    }

    public function getEtcDir()
    {
        //return $this->getDataSetDefault('etc_dir', $this->getAppDir().DS.'etc');
        return $this->_data['etc_dir'];
    }

    public function getLibDir()
    {
        //return $this->getDataSetDefault('lib_dir', $this->getBaseDir().DS.'lib');
        return $this->_data['lib_dir'];
    }

    public function getLocaleDir()
    {
        //return $this->getDataSetDefault('locale_dir', $this->getAppDir().DS.'locale');
        return $this->_data['locale_dir'];
    }

    public function getMediaDir()
    {
        //return $this->getDataSetDefault('media_dir', $this->getBaseDir().DS.'media');
        return $this->_data['media_dir'];
    }

    public function getSkinDir()
    {
        //return $this->getDataSetDefault('skin_dir', $this->getBaseDir().DS.'skin');
        return $this->_data['skin_dir'];
    }

    public function getSysTmpDir()
    {
        return sys_get_temp_dir();
    }

    public function getVarDir()
    {
        //$dir = $this->getDataSetDefault('var_dir', $this->getBaseDir().DS.'var');
        $dir = isset($this->_data['var_dir']) ? $this->_data['var_dir']
            : $this->_data['base_dir'] . DS . self::VAR_DIRECTORY;
        if (!$this->createDirIfNotExists($dir)) {
            $dir = $this->getSysTmpDir().DS.'magento'.DS.'var';
            if (!$this->createDirIfNotExists($dir)) {
                throw new Mage_Core_Exception('Unable to find writable var_dir');
            }
        }
        return $dir;
    }

    public function getTmpDir()
    {
        //$dir = $this->getDataSetDefault('tmp_dir', $this->getVarDir().DS.'tmp');
        $dir = $this->_data['tmp_dir'];
        if (!$this->createDirIfNotExists($dir)) {
            $dir = $this->getSysTmpDir().DS.'magento'.DS.'tmp';
            if (!$this->createDirIfNotExists($dir)) {
                throw new Mage_Core_Exception('Unable to find writable tmp_dir');
            }
        }
        return $dir;
    }

    public function getCacheDir()
    {
        //$dir = $this->getDataSetDefault('cache_dir', $this->getVarDir().DS.'cache');
        $dir = $this->_data['cache_dir'];
        $this->createDirIfNotExists($dir);
        return $dir;
    }

    public function getLogDir()
    {
        //$dir = $this->getDataSetDefault('log_dir', $this->getVarDir().DS.'log');
        $dir = $this->_data['log_dir'];
        $this->createDirIfNotExists($dir);
        return $dir;
    }

    public function getSessionDir()
    {
        //$dir = $this->getDataSetDefault('session_dir', $this->getVarDir().DS.'session');
        $dir = $this->_data['session_dir'];
        $this->createDirIfNotExists($dir);
        return $dir;
    }

    public function getUploadDir()
    {
        //$dir = $this->getDataSetDefault('upload_dir', $this->getMediaDir().DS.'upload');
        $dir = $this->_data['upload_dir'];
        $this->createDirIfNotExists($dir);
        return $dir;
    }

    public function getExportDir()
    {
        //$dir = $this->getDataSetDefault('export_dir', $this->getVarDir().DS.'export');
        $dir = $this->_data['export_dir'];
        $this->createDirIfNotExists($dir);
        return $dir;
    }

    public function createDirIfNotExists($dir)
    {
        if (!empty($this->_dirExists[$dir])) {
            return true;
        }
        if (file_exists($dir)) {
            if (!is_dir($dir)) {
                return false;
            }
            if (!is_dir_writeable($dir)) {
                return false;
            }
        } else {
            $oldUmask = umask(0);
            if (!@mkdir($dir, 0777, true)) {
                return false;
            }
            umask($oldUmask);
        }
        $this->_dirExists[$dir] = true;
        return true;
    }
    
    protected function getStoreName()
    {
        if(!empty($_SERVER['MAGE_RUN_TYPE'])) {
            $type = $_SERVER['MAGE_RUN_TYPE'];
        } else { $type = "base"; }
        
        if(!empty($_SERVER['MAGE_RUN_CODE'])) {
            $name = $_SERVER['MAGE_RUN_CODE'];
        } else { $name = "base"; }
        
        if($name == $type) {
            return '';
        }
        
        return DS.$type.DS.$name;
    }
}