>> On Unix System V, the link command would allow hard-linking >> directories when used as root.
Also, recently enough that at least some versions of NetBSD do it, unlink(2) performed by root on the last non-. link to a directory would silently orphan the directory, requiring fsck to fix. I've long thought this deserved to be considered a bug. > The reason being that hard links to directories means that the tree > of directories is no longer a DAG and that causes serious problems > for the tree traversing code. Well, might no longer be a DAG. I don't see why this couldn't be checked at link(2) time; it's checked within rename(2). I think a more-likely-relevant reason is that there's only one place .. can point, at least unless you allow multiple .. entries in the directory (which would fix this but open a different can of worms). Come to think of it, that could be relevant; if a directory can have multiple parents, walking parents until you get to the root becomes a much less obviously possible thing to do. /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML [email protected] / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
