Semantics of readdir's add_entry argument

[nrath-js]

I have not been able to find any documentation for the add_entry: &mut dyn FnMut(DirEntry<'_>) -> Result<usize> argument that is passed to readdir. Did I miss anything?

My best guess is that the return value represents a length, and that I need to check that the total length does not exceed the value of the size parameter. However, I am not sure if the return value is the length of the most recent entry (so I have to accumulate the total), or the total space used, or perhaps the remaining space?