Hard links to directories: why not?

[Bob Goudreau]

In article <YEV4:.9 at xds13.ferranti.com>, peter at ficc.ferranti.com (Peter
da Silva) writes:
> 
> We're only talking about letting users make hard links to directories. Not
> about deleting them. Root can always make files by playing games that find
> can't find... the question at hand here is if a user can. A user can't
> unlink a directory with unlink, so they can't build this structure even if
> they can make a hard link to a directory.

Don't be too sure that even the superuser can link() to or unlink()
from directories.  POSIX.1 doesn't require an implementation to
support link() and unlink() on directories, and implementations that
disallow such actions do indeed exist.
 
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