Subject: Alias storage of dir/file ID's
From: Richard Goldman (rgml@graphpoint.com)
Date: Fri Jun 08 2001 - 00:34:30 EDT
Jeff --
Sorry if this is your second receipt of my message (having trouble with my email system).
Also, a note here... I recompiled today's CVS (June 7), and tried it out with a well-formed afpd.mtab in the sysconfdir (/usr/local/atalk/etc for me). As I've mentioned before, I'm looking for a change in the 8 more-significant-bits of the 32-bit identifier in the alias.
Here's an example and an illustration that might assist in verifying the implementation of mtab code (decimal inodes returned by "ls -i filename" converted to hex):
To start, the old, non-mtab pattern is:
bit 1 (1 bit for file vs. directory)
bits 2-5 (4 bits for device major number)
bits 6-8 (3 bits for device minor number)
bits 9-32 (24 bits for inode)
I have a file (not a directory)
-- Therefore bit 1 is set to value 1
This file resides on...
device 9 major
-- Therefore bits 2-5 are set to 1001
device 0 minor
-- Therefore bits 6-8 are set to 000
This file exists at inode 073695h
-- Therefore bits 9-32 are set to...
0 7 3 6 9 5
0000 0111 0011 0110 1001 0101
Append these all together and you get (dot separators for emphasis):
F Maj Min Inode
1.1001.000.000001110011011010010101
Now compact them together, and take the hex of each block of 4 bits (nibble?)...
11001000000001110011011010010101 =
1100 1000 0000 0111 0011 0110 1001 0101 =
C 8 0 7 3 6 9 5
So here's the payoff: If you open this alias with Apple's resedit utility (check the "Use alias instead of original" box), you'll find that starting at byte position 000072 you have the digits:
C807 3695 (as above!)
So, using this analysis, it appears that mtab code isn't applying here, as the result with mtab active would be:
2007 3695 (coming from a run of test_parse_mtab where my drive is listed as "1 /dev/md0 /" in the mtab).
A note: test_parse_mtab likes to have an afpd.mtab file in the same directory (so I copied it from /usr/local/atalk/etc).
I hope this helps!
---------- Original Message ----------------------------------
From: "Richard Goldman" <rgml@graphpoint.com>
Reply-To: <rgml@graphpoint.com>
Date: Thu, 7 Jun 2001 12:52:44 -0400
>Jeff --
>
>Yes, I did compile with "--with-did=mtab" (on CVS tree taken at 10am PDT yesterday). The reason I'm not sure if it's working is that I had created an alias using an older version of netatalk. I then compiled the new tree with the above option, created a valid afpd.mtab (in atalk/etc) and made a fresh alias. When I compared the contents of these pre and post mtab aliases, there was no difference between the two in the vicinity of byte 70 (as seen in resedit).
>
>I'm just guessing that the leading bits prior to byte 73 (start of 24 bit inode) would be different if mtab were active because mtab promises a greater number of bits dedicated to inode only.
>
>Apologies in advance for any incorrect assumptions, including my assumption that afpd.mtab should be in /usr/local/atalk/etc (that was my "--prefix=" location given during ./configure).
>
>BTW I'm thrilled that we're moving along in this area and I truly appreciate the focus you and others give to this and all other aspects of netatalk. Thank you for taking the time to oversee its continuing improvement.
>
>-- Richard
>
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