PHP extract a subdirectory contained in a ZIP file to a destination path

extract_zip_subdir.php

<?php
function extract_zip_subdir($zipfile, $subpath, $destination, $temp_cache, $traverse_first_subdir=true){
	$zip = new ZipArchive;
	echo "extracting $zipfile... ";
	if(substr($temp_cache, -1) !== DIRECTORY_SEPARATOR) {
		$temp_cache .= DIRECTORY_SEPARATOR;
	}
	$res = $zip->open($zipfile);
	if ($res === TRUE) {
	    if ($traverse_first_subdir==true){
	        $zip_dir = $temp_cache . $zip->getNameIndex(0);
	    }
	    else {
	    	$temp_cache = $temp_cache . basename($zipfile, ".zip");
	    	$zip_dir = $temp_cache;
	    }
	    echo "  to $temp_cache... \n";
	    $zip->extractTo($temp_cache);
	    $zip->close();
	    echo "ok\n";
	    echo "moving subdir... ";
	    echo "\n $zip_dir / $subpath -- to -- >  $destination\n";
	    rename($zip_dir . DIRECTORY_SEPARATOR . $subpath, $destination);
	   	echo "ok\n";
	    echo "cleaning extraction dir... ";
	    rrmdir($zip_dir);
	    echo "ok\n";
	} else {
	    echo "failed\n";
	    die();
	}
}
?>

if(substr($temp_cache, -1) !== DIRECTORY_SEPARATOR) can be rewritten as rtrim($x, DIRECTORY_SEPARATOR)