Bug#107826: can not create file through a dangling symlink

[Thomas Bushnell, BSG]

Roland McGrath <roland@gnu.org> writes:

> The specification is for all pathname translation--it always works the
> same, no matter what particular functions you are using.  In the Hurd
> implementation, this all happens in the hurd_file_name_lookup functions
> (libc/hurd/hurdlookup.c) or in the dir_lookup RPC server.  I think that all
> we need to change right now to match this new spec is to insert a check for
> "" in hurd_file_name_lookup and hurd_file_name_split.

The current interface deliberately invokes lookups of "" for various
important cases.  Turning that off in dir_lookup will break much, so
it must be done in the library.