H5G_LINK creates a new name for an object that has some current name, possibly one of many names it currently has.
current_name must specify the name of an existing object and both names are interpreted relative to
loc_id, which is either a file identifier or a group identifier.
current_name can be anything and is interpreted at lookup time relative to the group which contains the final component of
new_name. For instance, if
./x/y/bar, and a request is made for
./x/y/bar, then the actual object looked up is