Gets us rid of integer overflows resulting in negative sizes which
aren't correctly checked.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>