tomcode/CodeIgniter — comment on commit 98f85b177d6ebf6dbc3a2ec8313ef738eca2fbf2
File: system/libraries/Zip.php line 103
By Eclarian:

You shouldn't need filemtime at all in your conditional. It only duplicates the function call. If file_exists is false, it will never call the second conditional and if it is true, then filemtime will not return FALSE unless there are user access issues associated with the file itself. In this case, you want to see the error so you can correct the situation. This problem with the file would then come down to the underlying functions used by your server to access that file.

This line should be as follows:

$date = (file_exists($dir)) ? filemtime($dir): getdate($this->now);