XML Caching

[scrupul0us]

<?php
function xmlGetFeed($url)
{
	if(false === $xml = @file_get_contents($url))
	{
		$xml = '';
		die('Could not retrieve feed from: '.$url);
	}
	else
	{
		define('XML_DATA', file_get_contents($url));
	}
	if(false === $xml = @simplexml_load_string(XML_DATA))
	{
		$xml = '';
		die('The feed provided is not valid XML');
	}
	else
	{
		return XML_DATA;
	}
}

function xmlCached($path,$file,$url,$time) //URL,FILE_NAME,PATH,TIME
{
	define('SCRIPT_ROOT',dirname(__FILE__).'\\');

if(empty($path)) //USE SCRIPT ROOT
{
	if(!is_writable(SCRIPT_ROOT))
	{
		die('The cache directory: '.SCRIPT_ROOT.' is not writable');			
	}
	else
	{
		define('XML_CACHE_DIR',SCRIPT_ROOT);
	}
}
else
{
	if(file_exists($path))
	{
		if(!is_writable($path))
		{
			die('The cache directory: '.$path.' is not writable');			
		}
		else
		{
			define('XML_CACHE_DIR',$path);
		}
	}
	else
	{
		if(!mkdir($path))
		{
			die('Could not create the path: '.$path);
		}
		else
		{
			define('XML_CACHE_DIR',$path);
		}
	}
}

if(empty($file)) //NO FILENAME SPECIFIED
{
	define('XML_CACHE_FILE','default.xml');
}
else
{
	define('XML_CACHE_FILE',$file);
}

define('XML_CACHE_PATH',XML_CACHE_DIR.'\\'.XML_CACHE_FILE);

if(file_exists(XML_CACHE_PATH))
{
	if(!is_writable(XML_CACHE_PATH))
	{
		die(XML_CACHE_FILE.' is not writable in: '.XML_CACHE_DIR);
	}
	else
	{
		define('XML_MODIFIED',filemtime(XML_CACHE_PATH));
		define('XML_AGE',time() - XML_MODIFIED);
	}
}
else
{
	define('XML_MODIFIED',FALSE);
	define('XML_AGE',FALSE);
}

if(empty($time))
{
	define('XML_LIFETIME',3600);
}
else
{
	define('XML_LIFETIME',$time);
}

if(empty($url))
{
	die('Please specify a XML feed to cache');
}
else
{
	define('XML_URL',$url);
}

if(!XML_MODIFIED || !XML_AGE) //FILE DOESNT EXIST
{
	file_put_contents(XML_CACHE_PATH,xmlGetFeed(XML_URL));
	return simplexml_load_file(XML_CACHE_PATH);
}
elseif(XML_AGE > XML_LIFETIME) //EXPIRED, UPDATE IT
{
	file_put_contents(XML_CACHE_PATH,xmlGetFeed(XML_URL));
	return simplexml_load_file(XML_CACHE_PATH);
}
else
{
	return simplexml_load_file(XML_CACHE_PATH);
}	
}
$xml = xmlCached('g:\\test','','http://www.woot.com/blog/rss.aspx','',''); //URL,FILE_NAME,URL,TIME

print_r($xml);
?>

Comments? I tried to be thorough in the testing for permissions and expected return types