Yours is a disk filter, above disk.sys but below file-system drivers?
The file may not be memory-mapped by Notepad, but it is likely cached.
Read IRPs or fast-I/O to the FSD above you will be satisfied from cache
(that was populated by the 4k read you did see). So, no more disk I/O
is necessary.
Dave Cox
Hewlett-Packard Co.
HPSO/SSMO (Santa Barbara)
https://ecardfile.com/id/Dave+Cox
-----Original Message-----
From: Ho Mun Chuen [mailto:xxxxx@pmail.ntu.edu.sg]
Sent: Thursday, May 04, 2000 6:31 PM
To: File Systems Developers
Subject: [ntfsd] Re: Help needed regarding disk filter driver.
for an app like Wordpad, i first encountered a read irp for 2 bytes which
resulted in a read irp i supposed from vmm for 4k (because it is only after
this 4k is returned then the 2 bytes is returned). subsequently, i receive
read irps for small amounts of data. however, i never did encounter any read
irps for anything that might suggest as the text in the wordpad .doc file.
so i presume that filemapping is the reason. i think after the 4k is read
and mapped, Wordpad need not issue any read irps for the file’s data
anymore. moreover, if i open the file a second time, i don’t even receive
the 4k read although i still receive the reads for the small amounts of
data.
i am also trying to encrypt on write and decrypt on read. but if i don’t
receive the reads properly, i will have problem decrypting…
Ho Mun Chuen
@@ “Not everything that counts can be counted;
<” )~ and not everything that can be counted counts"
//\ … Albert Einstein
----- Original Message -----
From: Pavel Hrdina
To: File Systems Developers
Sent: Friday, May 05, 2000 12:15 AM
Subject: [ntfsd] Re: Help needed regarding disk filter driver.
Which problem do you mean?
Paul
> -----P?vodn? zpr?va-----
> Od: Ho Mun Chuen [SMTP:xxxxx@pmail.ntu.edu.sg]
> Odesl?no: 4. kv?tna 2000 11:22
> Komu: File Systems Developers
> P?edm?t: [ntfsd] Re: Help needed regarding disk filter driver.
>
> have u ever encountered file mapping problem?
>
> Ho Mun Chuen
> @@ “Not everything that counts can be counted;
> <” )~ and not everything that can be counted counts"
> //\ … Albert Einstein
> ----- Original Message -----
> From: Amit Gorantivar
> To: File Systems Developers
> Sent: Wednesday, May 03, 2000 7:40 PM
> Subject: [ntfsd] Re: Help needed regarding disk filter driver.
>
>
> Hi,
>
> Actually that problem is because of caching.so i solve it by a simple way.
> actually when I was trying to
> write the data on disk, i encrypt it.So on completion of the request i
> was
> getting back the
> encrypted data, Which is going to be stored on the cache. Next time when i
> try to read the file i read
> from the cache and file was in encrypted form.
> so the simple solution was i decrypted the user data on completion
> routine.
> that means
> in cache always having unencrypted data.
>
> thanks
> Ashish Maliye
>
>
> -----Original Message-----
> From: Ho Mun Chuen
> To: File Systems Developers
> Date: Wednesday, May 03, 2000 11:34 AM
> Subject: [ntfsd] Re: Help needed regarding disk filter driver.
>
>
> >how did u solve the prob? by changing to encrypt disk rather than files?
> >
> >Ho Mun Chuen
> >Advanced Technology Solutions Centre
> >CSO Development Laboratory
> >(Office) 3732426 (Pager) 93253507
> > @@ “Not everything that counts can be counted;
> ><” )~ and not everything that can be counted counts"
> > //\ … Albert Einstein
> >----- Original Message -----
> >From: Amit Gorantivar
> >To: File Systems Developers
> >Sent: Wednesday, April 26, 2000 8:19 PM
> >Subject: [ntfsd] Help needed regarding disk filter driver.
> >
> >
> >Hello friends,
> >
> >Thanks friends ,I am able solve the problem now.
> >
> >Till now I was trying to do encryption and decryption with some files
> >which is having a particular string (the driver is doing this
> >successfully).
> >
> >Now I am trying to do the same with the whole drive. So I applied my
> >encryption and decryption for all the read and write request to the
> >drive. When I tried to access the drive I got error “The volume does not
> >contain a recognized file system”. I think It is because of my driver,
> >which try to decrypt the data, since data read is not in encrypted form,
> >data gets corrupted and error occurred.
> >
> >Then I tried to format the drive and got error “Windows NT was unable to
> >complete the format.” On deleting the partition I got exception
> >“NTSTATUS=STATUS_ACCESS_VIOLATION”. How can I solve this problem?
> >
> >Thanks in advance
> >
> >Ashish
> >
> >
> >
> >Thanks again for helping me. Now I am able to update the data of the
> >MDL. I referred Disk Performance monitor to develop my driver. As I sad
> >I want to encrypt the data while writing and decrypt the data on
> >reading. I observed driver is trapping the read and write request to the
> >disk. Problem is there is some inconsistency between the read and write
> >request.
> >
> >Suppose I want to open a file from a drive on the very first time driver
> >gets read request, but next time if I want to open the same file it is
> >not getting any request. But every time I want to save the file, driver
> >gets the write request. How can I eliminate this inconsistency , which
> >is creating a great problem for doing encryption and decryption
> >properly.
> >
> >
> >
> >
> >—
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> >
>
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