> .. but there remained one that garbled meta-data had made into a
> non-existing block device, that would resist rm -f.  He realized
> that the device had an immutable attribute.  However, the problem is
> that to change the attribute, you have to open the file before you
> can ioctl() on it;

BSD4.4 and its progeny deal with this by providing both chflags() and
fchflags() system calls; as you don't need to be able to do an open()
call to use chflags(), you can just fix the immutable attribute once
you have the system running at an appropriate securelevel.

					- Bill