Iterate Up the HR Structure

Thanks to Kat for this one... I've got to get the UserID of the Users Manager... trouble is, sometimes the OrgStructure positions aren't filled - so I have to see who's sitting in the position. If there's no-one in it, then I loop back round and get the OrgStructure's superior position (since there's no Personnel person to check on!). I repeat this until I find someone, and stop at 20 goes... If this has happened, it's either 

the guy at the top of the tree (we try 20 times to work out if the guy has a useful boss, but fail because it's Paul Solomon :) 

OR

there's such a massive Org Structure that's not populated with stuff, that you should probably question what the point of the structure is!!

do 20 times.  "Don't want to infinite loop...
refresh t_leadpos.
CALL FUNCTION 'RH_GET_LEADING_POSITION'
    EXPORTING
      plvar            = w_plvar
      otype            = l_otype  "can be US (user), P (Person), S (position) or O (Org unit)
      sobid            = l_sobid
      date             = sy-datum
      auth             = ' '
    TABLES
      leading_pos    = t_leadpos
    EXCEPTIONS
      no_lead_pos_found  = 1
      OTHERS             = 2.

check t_leadpos[] is not initial.
read table t_leadpos into w_leadpos index 1.

      REFRESH t_holders.
      CALL FUNCTION 'HRWPC_RFC_PP_HOLDERS'
        EXPORTING
          plvar           = w_plvar          "usually 01
          otype           = 'S'
          objid           = w_leadpos-objid   "from above table read
        TABLES
          holder          = t_holders
        EXCEPTIONS
          no_active_plvar = 1
          infty_not_found = 2
          nothing_found   = 3
          OTHERS          = 4.

      IF sy-subrc = 0 AND t_holders IS NOT INITIAL.

        READ TABLE t_holders INTO w_holders INDEX 1.

      read table t_pa0105 into w_pa0105 with key pernr = w_holders-pernr
                                                  subty = '0001'.
      if sy-subrc = 0.
          p_output-manager = w_pa0105-usrid.
          exit.
      endif.

      else. "Didn't find holders for the position... Go and find the Super-Position.
         l_otype = w_leadpos-otype. "Probably 'S' but hey, let's make it dynamic.
         l_sobid = w_leadpos-objid.
      endif.  "Found holders for the position.

enddo. "Iterate up the structure.