(PHP 5 >= 5.2.0, PECL zip >= 1.5.0)
ZipArchive::renameIndex — Renames an entry defined by its index
$index
   , string $newname
   )Renames an entry defined by its index.
indexIndex of the entry to rename.
newnameNew name.
   Returns TRUE on success or FALSE on failure.
  
Example #1 Rename one entry
<?php
$zip = new ZipArchive;
$res = $zip->open('test.zip');
if ($res === TRUE) {
    $zip->renameIndex(2,'newname.txt');
    $zip->close();
} else {
    echo 'failed, code:' . $res;
}
?>