Current Directory Structure (CDS)

>> locate the SAS file system section
##dw 70:12 l1
0070:00000012  0074
##dw 70:74
0070:00000074  0fa4 fe70 00c0 07f8 0828 00a8 0428 0000
0070:00000084  03c8 ffff ffff 0843 0000 0000 0000 0000
0070:00000094  0000 0000 0000 0000 0000 0000 0000 0000
0070:000000a4  0000 0000 0000 0000 0000 0000 0000 0000
0070:000000b4  0000 0000 0000 0000 0000 0000 0000 0000
0070:000000c4  0000 0000 0000 0000 0000 0000 0000 0000
0070:000000d4  0000 0000 0000 0000 0000 0000 0000 0000
0070:000000e4  0000 0000 0000 0000 0000 0000 0000 0000

>> +8 into the file system section is the CDS RMP selector.
>> Can verify this by checking out the memory object owner.

##.m 828:0

*har     par      cpg        va    flg next prev link hash hob   hal
 0003 %feaef04c 00000400 %fe6ef000 001 0002 0023 0000 0000 0003 0000      =0000
 hob   har hobnxt flgs own  hmte  sown,cnt lt st xf
 0003  0003 fec5  0000 ffec 0000  0000 00  01 00 00 vmkrhrw
   pvmli    cs    eip     phlock   cpg      va    flg  hptda hob sig  csig
 %fe82e4c4 002d 0a6800a5 %ac22403c 0001 %fe83c000 0005 024b 0003 ea9f ea9f

>> Owned by the Kernel Resident Heap. Look at the header

##dd %(828:0)-10 l8
%fe7015b4  000007d0 ff5c07b0 0000bd64 0000060d
%fe7015c4  049d0600 01ae0014 00000001 00000400

>> This is an attributed block so look at the trailer

##dd %(828:0)-10-4+60c l8
%fe701bbc  00000000 00000000 ff610828 0000fe70
%fe701bcc  ff9e0054 4d45534b 00000201 00000000

##.mo ff61
ff61 cdsrmp

>> 828 does indeed point to the CDS RMP


>> Now dump the CDS handle table for the process of interest
##.p#
 Slot  Pid  Ppid Csid Ord  Sta Pri  pTSD     pPTDA    pTCB     Disp SG Name
 0048# 0029 0004 0029 0001 blk 0200 ab805000 ab99b820 ab97fc20 1ed4 11 cmd


##dw %ab99b820 +cds_handle-ptda_start l1a
%ab99bac8  0000 0000 0000 0000 0000 0000 0000 0090
%ab99bad8  0000 0000 0000 0000 0000 0000 0000 0000
%ab99bae8  0000 0000 0000 0000 0000 0000 0000 0000
%ab99baf8  0000 0000

>> Except for driver 07 (H:) the current directory handle is null.
>> This implies that the current directory for drive H: is not the
>> root. To see which it is, we need to locate the the CDS entry with
>> handle 0x0090.


>> The RMP has a 0x14 byte header. Each entry is prefixed with a word
>> length followed by the handle for that entry.

>> Starting with the first entry scan through until handle 0x0090 is
>> located.

##dw 828:14 l4
0828:00000014  8028 0000 00b2 0000

##dw 828:14 l2
0828:00000014  8028 0000

##dw 828:14+28 l2
0828:0000003c  0028 001c

##dw 828:14+28+28 l2
0828:00000064  0028 001d

##dw 828:14+28+28+28 l2
0828:0000008c  0026 001e

##dw 828:14+28+28+28+26 l2
0828:000000b2  8023 0014

##dw 828:14+28+28+28+26+23 l2
0828:000000d5  0028 0022

##dw 828:14+28+28+28+26+23+28 l2
0828:000000fd  002e 008f

##dw 828:14+28+28+28+26+23+28+2e l2
0828:0000012b  0025 0090

>> The CDS starts after the length prefix.

##.d cds 828:12b+2
   cd_handle: 0090                          cddFAT_id: 0000
   cd_refcnt: 0002
    cd_flags: 40
   cd_devptr: 04b8:00c4
 cd_OwnerFSC: 0008

    cdi_hVPB: 0012
     cdi_end: 0002
   cdi_flags: 80
    cdi_text: H:\spool
##

Notes:

The selector for the CDS segment may be located from the SAS, as illustrated above, or form the storage at label CDSAddr.

The CDS RMP has a unique owner ID, which may be determined using the .M command.. In the case of the CDS RMP, it is allocated from the kernel resident heap, so the true owner id is found in the heap header (or its extension - the trailer).

For a description of the CDS fields see the Current Directory Structure (CDS) in the System Reference.