Upload, but no overwrite

[Re4zOon]

Hi!
I want to give permissions to upload files, but no overwrite or rename or delete or anything. If the user uploaded a file once, he/she won't be able to change the file(s), so if they want to do correction, they need to upload it again with different name.
How can i do it?

[FTP]

You can't prevent upload overwrite.