NAME
    ParentDir -- Obtain the parent of a directory or file

SYNOPSIS
    newlock = ParentDir( lock )
    D0                   D1

    BPTR ParentDir(BPTR)

FUNCTION
    The argument 'lock' is associated with a given file or directory.
    ParentDir() returns 'newlock' which is associated the parent
    directory of 'lock'.

    Taking the ParentDir() of the root of the current filing system
    returns a NULL (0) lock.  Note this 0 lock represents the root of
    file system that you booted from (which is, in effect, the parent
    of all other file system roots.)

INPUTS
    lock - BCPL pointer to a lock

RESULTS
    newlock - BCPL pointer to a lock

SEE ALSO
    lock(), duplock(), unlock(), parentoffh(), duplockfromfh()