lib/Util/AttachmentUtils.php
public static function findUniqueName($name, array $claimed)
    {
        $ext = pathinfo($name, \PATHINFO_EXTENSION);
        $basename = substr($name, 0, -strlen('.'.$ext));

        $i = 0;
        while (in_array($name, $claimed)) {
            $i++;
            $name = $basename.'-'.$i.'.'.$ext;
        }

        return $name;
    }
public static function findUniqueName($name, array $claimed)
    {
        $ext = pathinfo($name, \PATHINFO_EXTENSION);
        $basename = substr($name, 0, -strlen('.'.$ext));

        $i = 0;
        while (in_array($name, $claimed)) {
            $i++;
            $name = $basename.'-'.$i.'.'.$ext;
        }

        return $name;
    }
@param string $name    The name to make unique
@param array  $claimed Names already in use to avoid

@return string A unique name