Host: Weird things can happen if VMU added or removed after host reads and caches mass storage FAT

[Tails86]

When the file system adds or removes a file, it sends UNIT ATTENTION to the host so it knows something changed. Windows, however, does not reread the FAT, even when F5 is pressed. I've found some help in resending UNIT ATTENTION until read of FAT is detected, but it only works once. I haven't confirmed if the host is actually receiving UNIT ATTENTION.

Figure out what needs to be done in order to force Windows to recheck the FAT.

[Tails86]

There seems to be no reliable way to accomplish this. I don't want to force a disconnect, so it may be best just to always show 8 devices when the drive attaches. Trying to read vmu that is not attached should then cause an error.

[Tails86]

It seems like the consensus on stack overflow and other sites that it is bad practice for a mass storage device to modify itself while attached to the host. Seems right to me 😆 I'm changing the purpose of this issue.

[Tails86]

Purpose:

• All 8 possible VMUs to be presented to the host when any memory unit is detected
  • Cause error if attempt is made to read from/write to a VMU which is not connected
• Allow host to modify the FAT in any way it would like as long as it's only trying to create or modify entries which have the same file name as something already on the file system
  • Internally use the FAT as "truth" in order to determine where to write to
  • Cause error if FAT is modified for a VMU which is not connected
  • Cause error if memory attempts to be written outside of VMU memory range