NAME
    DupLockFromFH -- Gets a lock on an open file (V36)

SYNOPSIS
    lock = DupLockFromFH(fh)
    D0                   D1

    BPTR DupLockFromFH(BPTR)

FUNCTION
    Obtain a lock on the object associated with fh.  Only works if the
    file was opened using a non-exclusive mode.  Other restrictions may be
    placed on success by the filesystem.

INPUTS
    fh   - Opened file for which to obtain the lock

RESULT
    lock - Obtained lock or NULL for failure

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