Programmatically differentiating between USB Floppy Drive and USB Flash Drive in Windows

Question

On Windows (XP-7), is there a reliable way of programatically differentiating between USB floppy drives and USB flash drives in C++?

At the moment, I'm using WMI to get updates when new Win32_LogicalDisk instances are detected, and then using the DriveType attribute of the LogicalDisk object to figure out a basic type. This works quite well, except that floppy drives and USB flash drives are both of DriveType DRIVE_REMOVABLE, so to differentiate between those (floppy vs. flash), I'm using the IOCTL_STORAGE_GET_HOTPLUG_INFO interface to figure out if the device is hotpluggable, and was working on the principal that that meant it was a flash drive and not a floppy. Again, I think this works quite well (if a little inefficient, using both the WDK API and WMI to get info ) in the case of internal floppy drives, but unfortunately USB Floppy drives are also hotpluggable a lot of the time, so there is no clear way to differentiate between flash and USB floppy drives, that I can see. I know there are properties that may work, like checking if its mapped to the reserved drives A: or B (edit: only relevant if the machine definitely has a floppy drive - see MS-KB: How to change drive letter assignments in Windows XP), or looking at the description, but I'd really like something a bit more reliable.

Sorry about the long explanation, but just wanted to be clear! Thanks

Answer 1

Did you try Win32_LogicalDisk.MediaType? It has specific enumerations for floppy disks. Make sure you try it when there's no disk in the drive.

Answer 2

On the USB level, there is no way to differentiate between a conventional Disk on Key and a USB-Floppy. Which means windows itself, cannot tell reliably what is what.

There are a few hints that you can gather: Floppies should: a. Have mass-storage protocol CBI/CB b. SCSI UFI

BUT, in the world of USB devices, everyone does whatever they want. The only test is: "Does it work on windows". And Windows just checks the size, if its a USB device with removable-media set and with conventional floppy sizes, it will consider it to be a floppy.

Can't say about "real" floppy, but with the USB attached, there is no definite way.

Answer 3

The obvious property to check would be IOCTL_DISK_GET_DRIVE_GEOMETRY. This gets you (amongst other things) a MEDIA_TYPE. Anything but RemovableMedia and FixedMedia is a floppy.

Answer 4

You can use the Size attribute (USB > 1.4MB), it's not like there is any chance of meeting 1.4MB flash drive any time soon.