Hi, we’re asked to make external volumes( such as USBs, hard drives) write only(only some users should see files inside it). In SET_DISK_ATTRIBUTES page (https://docs.microsoft.com/en-us/windows/win32/api/winioctl/ns-winioctl-set_disk_attributes) I can only see DISK_ATTRIBUTE_READ_ONLY. Can we conclude that WRITE_ONLY is not available?
Correct.
Some systems support write only media, but not Windows. And that’s probably not what you actually want because its uses are quite limited. It would be completely impossible to mount any normal file system for example since they all need to read at least some data from the disk
presumably this is some kind of security product, so suggesting that you simply set proper ACLs on the files or directories probably does not meet your needs.
so presumably, what you want to do is filter so that you can fail certain accesses with access denied. how exactly to do that will depend on the parameters of your higher level goal