Allows to open disk from already existing os.File descriptor

aol NB: i.e. in gin-disk

diskfs.go

@@ -332,6 +332,11 @@ func Open(device string, opts ...OpenOpt) (*disk.Disk, error) {
 	return initDisk(f, ReadWriteExclusive, opt.sectorSize)
 }
 
+func OpenFile(f *os.File) (*disk.Disk, error) {
+	opt := openOptsDefaults()
+	return initDisk(f, ReadOnly, opt.sectorSize)
+}
+
 // Create a Disk from a path to a device
 // Should pass a path to a block device e.g. /dev/sda or a path to a file /tmp/foo.img
 // The provided device must not exist at the time you call Create()