Compare PHP RecursiveIteratorIterator use with FilterIteractors

RecursiveDirectoryIterator-test.php

<?php

/*
Filesystem layout of ./backup/
total 0
drwxrwxr-x  3 kabel  staff  102 Apr 20 16:00 db
drwxrwx--x  3 root   wheel  102 Apr 20 16:31 do-not-backup

./db:
total 8
-rw-rw-r--  1 kabel  staff  1 Apr 20 16:00 foo

./do-not-backup:
total 0
-rw-r--r--  1 kabel  staff  0 Apr 20 16:31 bar
 */

/**
 * @author kabel
 *
 * @method RecursiveDirectoryIterator getInnerIterator()
 * @method SplFileInfo current()
 */
class RecursiveDirectoryFilterIterator extends RecursiveFilterIterator
{
    protected $_filters;

    public function __construct(RecursiveDirectoryIterator $iterator, array $filters = array())
    {
        parent::__construct($iterator);
        $this->_filters = $filters;
    }

    public function accept()
    {
        $current = (string)$this->current();
        $currentFilename = $this->current()->getFilename();

        if ($currentFilename == '.' || $currentFilename == '..') {
            return false;
        }

        foreach ($this->_filters as $filter) {
            if (false !== strpos($current, $filter)) {
                return false;
            }
        }

        return true;
    }

    public function getChildren()
    {
        return new self($this->getInnerIterator()->getChildren(), $this->_filters);
    }
}

/* BEGIN file from the magento core - lib/Mage/Backup/Filesystem/Iterator/Filter.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_Backup
 * @copyright   Copyright (c) 2010 Magento Inc. (http://www.magentocommerce.com)
 * @license     http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */

/**
 * Filter Iterator
 *
 * @category    Mage
 * @package     Mage_Backup
 * @author      Magento Core Team <core@magentocommerce.com>
 */
class Mage_Backup_Filesystem_Iterator_Filter extends FilterIterator
{
    /**
     * Array that is used for filtering
     *
     * @var array
     */
    protected $_filters;

    /**
     * Constructor
     *
     * @param Iterator $iterator
     * @param array $filters list of files to skip
     */
    public function __construct(Iterator $iterator, array $filters)
    {
        parent::__construct($iterator);
        $this->_filters = $filters;
    }

    /**
     * Check whether the current element of the iterator is acceptable
     *
     * @return bool
     */
    public function accept()
    {
        $current = $this->current()->__toString();
        $currentFilename = $this->current()->getFilename();

        if ($currentFilename == '.' || $currentFilename == '..') {
            return false;
        }

        foreach ($this->_filters as $filter) {
            if (false !== strpos($current, $filter)) {
                return false;
            }
        }

        return true;
    }
}

/* END */

// Inner Filter <- good
$itr = new RecursiveIteratorIterator(new RecursiveDirectoryFilterIterator(
    new RecursiveDirectoryIterator(dirname(__FILE__) . '/backup'), array('do-not-backup')
), RecursiveIteratorIterator::CHILD_FIRST);
foreach ($itr as $filePath => $fileInfo) {
    echo $filePath . PHP_EOL;
}

// Outer Filter <- bad
$itr = new Mage_Backup_Filesystem_Iterator_Filter(new RecursiveIteratorIterator(
    new RecursiveDirectoryIterator(dirname(__FILE__) . '/backup'), RecursiveIteratorIterator::CHILD_FIRST
), array('do-not-backup'));

// This loop will throw an exception when it reaches the directory owned by root (permission denied)
// even though it is marked to be filtered out. FATAL ERROR :(
foreach ($itr as $filePath => $fileInfo) {
    echo $filePath . PHP_EOL;
}

It is important to note that this test REQUIRES the filesystem layout described at the top (specifically note that the do-not-backup directory is owned by a different user AND is not readable by my user).

This will produce output similar to:

/Users/kabel/phptest/backup/db/foo
/Users/kabel/phptest/backup/db
/Users/kabel/phptest/backup/db/foo
/Users/kabel/phptest/backup/db
PHP Fatal error:  Uncaught exception 'UnexpectedValueException' with message 'RecursiveDirectoryIterator::__construct(/Users/kabel/phptest/backup/do-not-backup): failed to open dir: Permission denied' in /Users/kabel/phptest/RecursiveDirectoryIterator-test.php:154
Stack trace:
#0 [internal function]: RecursiveDirectoryIterator->__construct('/Users/kabel/ph...', 0)
#1 [internal function]: RecursiveDirectoryIterator->getChildren()
#2 /Users/kabel/phptest/RecursiveDirectoryIterator-test.php(154): FilterIterator->next()
#3 {main}
  thrown in /Users/kabel/phptest/RecursiveDirectoryIterator-test.php on line 154