Wrong utf8_substr default param usage in filemanager.php

[anilex]

When having $length = 0 in

function utf8_substr($string, $offset, $length = 0) {
    return mb_substr($string, $offset, $length);
}

the utf8_substr($directory, strlen(DIR_IMAGE . 'data/')); used in filemanager controller return string with zero length.

So.. we should overwrite the default length value with null ie. utf8_substr($directory, strlen(DIR_IMAGE . 'data/'), null); or we should remove default value for $length

[danielkerr]

that code is not there!

https://github.com/opencart/opencart/blob/master/upload/system/helper/utf8.php