There's a slightly tweaked FAT16 implementation used on some Akai samplers. I've created an emulator of one of those samplers. It supports USB volume i/o with a custom FAT16 implementation. All of this works, but currently goes via the deprecated AuthorizationExecuteWithPrivileges for achieving raw USB volume access. The mechanism I specifically rely on currently is to, with elevated privileges, change the ownership of /dev/diskN, and then with normal privileges I can open a file handle against that disk device.
Yesterday I looked into migrating to SMJobBless, but it also turns out to be deprecated.
Does any of the macOS SDKs support my use case? Should I look into writing a DriverKit or IOKit driver?
Any tips or guidance would be appreciated. Ideally I can implement a flow where the user is only required to approve with admin privileges once and after that has raw block device access to a restricted set connected volumes -- FAT16/ms-dos volumes that have a special volume label, or a special flag set in the boot sector.