EA info

NTFSD
1

hi, i am writing an encryption filter driver on top of FS.

i read about EA info. can i use it to store my own info by sending set_info
irps to the FS below?

Ho Mun Chuen
xxxxx@pmail.ntu.edu.sg
@@ “Not everything that counts can be counted;
<” )~ and not everything that can be counted counts"
//\ … Albert Einstein

2

Hi,

Message text written by “File Systems Developers”

hi, i am writing an encryption filter driver on top of FS.

i read about EA info. can i use it to store my own info by sending set_info
irps to the FS below?
<

Yes, but not reliably. Don’t, do it, unless you can live with the
restrictions:

EA can’t be relied upon to be available with every file. New Windows 2000
features used by some of the shipped FSD’s (e.g. NTFS) limit the
availability of Extended Attributes. I seem to remember also that
FAT32 doesn’t support EA’s. So this solution is not generally applicable,
although it ‘might’ just work for
NT4.

In general, associating persistent private data with files in a filter is a
hard problem. The other options are going to be time consuming. So you
might want to live with these limitations and go with EA’s.

Jack Heeley
Chess IT

3

does FAT and NTFS under NT 4 support EA?

Ho Mun Chuen
xxxxx@pmail.ntu.edu.sg
@@ “Not everything that counts can be counted;
<” )~ and not everything that can be counted counts"
//\ … Albert Einstein
----- Original Message -----
From: “Jack Heeley”
To: “File Systems Developers”
Sent: Monday, October 16, 2000 7:01 PM
Subject: [ntfsd] EA info

Hi,

Message text written by “File Systems Developers”
>
hi, i am writing an encryption filter driver on top of FS.

i read about EA info. can i use it to store my own info by sending set_info
irps to the FS below?
<

Yes, but not reliably. Don’t, do it, unless you can live with the
restrictions:

EA can’t be relied upon to be available with every file. New Windows 2000
features used by some of the shipped FSD’s (e.g. NTFS) limit the
availability of Extended Attributes. I seem to remember also that
FAT32 doesn’t support EA’s. So this solution is not generally applicable,
although it ‘might’ just work for
NT4.

In general, associating persistent private data with files in a filter is a
hard problem. The other options are going to be time consuming. So you
might want to live with these limitations and go with EA’s.

Jack Heeley
Chess IT

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4

Message text written by “File Systems Developers”

does FAT and NTFS under NT 4 support EA?<

Yes they do.

Jack Heeley
Chess IT