ClearFD clears the loop device associated with file descriptor fd.

ClearFile clears the fd association of the loop device "devicename".

FindDevice finds an unused loop device and returns its /dev/loopN path.

GetFree finds a free loop device /dev/loopN.

New initializes a Loop struct and allocates a loodevice to it.

SetFD associates a loop device lfd with a regular file ffd.

SetFile associates loop device "devicename" with regular file "filename".

Loop represents a regular file exposed as a loop block device.