Aha ! The code retrieves the file object for the file mapping for file
‘y’ and assigns it’s SectionObjectPointer->DataSectionObject to the
corresponding field in the file object for file ‘x’. Hopefully that
solves the mystery. If so, thanks a lot for helping me see the light.
-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Tony Mason
Sent: Wednesday, April 20, 2005 10:01 AM
To: Windows File Systems Devs Interest List
Subject: RE: [SPAM] - Re: [ntfsd] No IRP_MJ_READ if I use ZwCreateFile -
Bayesian Filter detected spam
What are you setting in your file object’s Section Object Pointers
structure?
Regards,
Tony
Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
http://www.osr.com
-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Amitabh Mathrawala
Sent: Wednesday, April 20, 2005 12:53 PM
To: ntfsd redirect
Subject: RE: [SPAM] - Re: [ntfsd] No IRP_MJ_READ if I use ZwCreateFile -
Bayesian Filter detected spam
Actually, I realized I may not have done a great job explaining the
problem. Let me try again :
Notepad sends an irp_mj_create for a file named ‘x’ on the remote
machine down to my file system redirector (implements a pseudo file
system, in OSR’s language).
While processing the irp_mj_create, I open a file named ‘y’ on the local
disk and complete the irp for file ‘x’.
After that, I expect an irp_mj_read for the file named ‘x’ which never
comes in.
I just found out a workaround for this but I am still trying to
understand how this works. Somewhere in the code,before I complete the
irp_mj_create, I was creating a section for the file ‘y’ (for my own
memory mapping purposes). When I remove this memory mapping, I get the
irp_mj_reads as expected.
I guess I am trying to understand why would notepad’s memory mapping for
file ‘x’ refer to memory mapping for file ‘y’ ? In other words, how does
the IOmanager know that file 'x’s contents are really in the memory map
for file ‘y’ ?
Thanks a lot for your replies.
-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Maxim S.
Shatskih
Sent: Tuesday, April 19, 2005 7:15 PM
To: Windows File Systems Devs Interest List
Subject: [SPAM] - Re: [ntfsd] No IRP_MJ_READ if I use ZwCreateFile -
Bayesian Filter detected spam
Notepad uses memory-mapped files. So, monitor the noncached reads.
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com
----- Original Message -----
From: “Amitabh Mathrawala”
To: “Windows File Systems Devs Interest List”
Sent: Tuesday, April 19, 2005 10:18 PM
Subject: [ntfsd] No IRP_MJ_READ if I use ZwCreateFile
Hi Folks !
I am having an issue that might have been discussed long before but I
can’t seem to find it in the old posts.
I am writing a FSD (part of a pseudo file system) that calls
ZwCreateFile to open a file from the local disk when it gets an
IRP_MJ_CREATE. If Notepad is the application that sends the create irp
and while processing the irp if I call ZwCreateFile, then I don’t see
IRP_MJ_Reads from Notepad, but the file opens up with it’s encrypted
contents. I need those IRP_MJ_Reads so that I can decrypt the file. I
know that notepad uses memory mapped files which could be the reason
don’t see the irp_mj_reads. Is there anything I can do to get the
IRP_MJ_Reads from Notepad ?
I have tried specifying FILE_NO_INTERMEDIATE_BUFFERING in ZwCreateFile
but that didn’t make the difference. Please send me some suggestions or
point me in the right direction. I absolutely need to understand what’s
going on here.
Here are some specifics :
ZwCreateFile (&cache, FILE_READ_DATA | FILE_WRITE_DATA | SYNCHRONIZE,
&attr, &iosb, 0, FILE_ATTRIBUTE_HIDDEN, FILE_SHARE_READ |
FILE_SHARE_READ | FILE_SHARE_DELETE, FILE_OPEN_IF, options |
FILE_WRITE_THROUGH | FILE_SYNCHRONOUS_IO_ALERT, NULL, 0);
Thanks.
Amitabh Mathrawala | xxxxx@viack.com | 425 605 7483
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