How to get the system env variables inside a driver.

NTFSD
1

Hi,

I want to get the system environment variables like SystemRoot,
SystemDrive etc inside my driver.

How can I get it. Is it a well defined value or there is some call to
get it.

Regards,
Avinash

2

For what?

To access files in SystemRoot, just use the \SystemRoot\path pathname. It
works for kernel code.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

----- Original Message -----
From: “Avinash Kumar”
To: “Windows File Systems Devs Interest List”
Sent: Thursday, February 05, 2004 1:12 AM
Subject: [ntfsd] How to get the system env variables inside a driver.

> Hi,
>
> I want to get the system environment variables like SystemRoot,
> SystemDrive etc inside my driver.
>
> How can I get it. Is it a well defined value or there is some call to
> get it.
>
> Regards,
> Avinash
>
> —
> Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>

3

Thanks Max,

I wanted to use SystemDrive instead of SystemRoot to build my path
information. Will that work? I’ll give that a try.

Regards,
Avinash

-----Original Message-----
From: Maxim S. Shatskih [mailto:xxxxx@storagecraft.com]
Sent: Wednesday, February 04, 2004 5:25 PM
To: Windows File Systems Devs Interest List
Subject: Re: [ntfsd] How to get the system env variables inside a
driver.

For what?

To access files in SystemRoot, just use the \SystemRoot\path
pathname. It works for kernel code.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

----- Original Message -----
From: “Avinash Kumar”
To: “Windows File Systems Devs Interest List”
Sent: Thursday, February 05, 2004 1:12 AM
Subject: [ntfsd] How to get the system env variables inside a driver.

> Hi,
>
> I want to get the system environment variables like SystemRoot,
> SystemDrive etc inside my driver.
>
> How can I get it. Is it a well defined value or there is some call to
> get it.
>
> Regards,
> Avinash
>
> —
> Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: xxxxx@storagecraft.com To
> unsubscribe send a blank email to xxxxx@lists.osr.com
>

—
Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

You are currently subscribed to ntfsd as: xxxxx@commvault.com To
unsubscribe send a blank email to xxxxx@lists.osr.com

4

It is a good design idea that all files accessed from the driver are
located under \SystemRoot.

Why not follow it?

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

----- Original Message -----
From: “Avinash Kumar”
To: “Windows File Systems Devs Interest List”
Sent: Thursday, February 05, 2004 1:36 AM
Subject: RE: [ntfsd] How to get the system env variables inside a driver.

> Thanks Max,
>
> I wanted to use SystemDrive instead of SystemRoot to build my path
> information. Will that work? I’ll give that a try.
>
> Regards,
> Avinash
>
>
>
> -----Original Message-----
> From: Maxim S. Shatskih [mailto:xxxxx@storagecraft.com]
> Sent: Wednesday, February 04, 2004 5:25 PM
> To: Windows File Systems Devs Interest List
> Subject: Re: [ntfsd] How to get the system env variables inside a
> driver.
>
>
> For what?
>
> To access files in SystemRoot, just use the \SystemRoot\path
> pathname. It works for kernel code.
>
> Maxim Shatskih, Windows DDK MVP
> StorageCraft Corporation
> xxxxx@storagecraft.com
> http://www.storagecraft.com
>
>
> ----- Original Message -----
> From: “Avinash Kumar”
> To: “Windows File Systems Devs Interest List”
> Sent: Thursday, February 05, 2004 1:12 AM
> Subject: [ntfsd] How to get the system env variables inside a driver.
>
>
> > Hi,
> >
> > I want to get the system environment variables like SystemRoot,
> > SystemDrive etc inside my driver.
> >
> > How can I get it. Is it a well defined value or there is some call to
> > get it.
> >
> > Regards,
> > Avinash
> >
> > —
> > Questions? First check the IFS FAQ at
> https://www.osronline.com/article.cfm?id=17
> >
> > You are currently subscribed to ntfsd as: xxxxx@storagecraft.com To
> > unsubscribe send a blank email to xxxxx@lists.osr.com
> >
>
>
> —
> Questions? First check the IFS FAQ at
> https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: xxxxx@commvault.com To
> unsubscribe send a blank email to xxxxx@lists.osr.com
>
> —
> Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>

5

I want to keep a file in system volume information so that no one
touches it by mistake too.

I am having this problem that if the file is opened by someone in
usermode ( even explorer ) my open is kernel fails. I am not sure why so
I felt let me keep it in system volume information where the chances are
very less for someone to browse/open.

Any idea why a Kmode File Open starts failing if someone opens it in the
user mode.

Regards,
Avinash

-----Original Message-----
From: Maxim S. Shatskih [mailto:xxxxx@storagecraft.com]
Sent: Wednesday, February 04, 2004 6:00 PM
To: Windows File Systems Devs Interest List
Subject: Re: [ntfsd] How to get the system env variables inside a
driver.

It is a good design idea that all files accessed from the driver are
located under \SystemRoot.

Why not follow it?

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

----- Original Message -----
From: “Avinash Kumar”
To: “Windows File Systems Devs Interest List”
Sent: Thursday, February 05, 2004 1:36 AM
Subject: RE: [ntfsd] How to get the system env variables inside a
driver.

> Thanks Max,
>
> I wanted to use SystemDrive instead of SystemRoot to build my path
> information. Will that work? I’ll give that a try.
>
> Regards,
> Avinash
>
>
>
> -----Original Message-----
> From: Maxim S. Shatskih [mailto:xxxxx@storagecraft.com]
> Sent: Wednesday, February 04, 2004 5:25 PM
> To: Windows File Systems Devs Interest List
> Subject: Re: [ntfsd] How to get the system env variables inside a
> driver.
>
>
> For what?
>
> To access files in SystemRoot, just use the \SystemRoot\path
> pathname. It works for kernel code.
>
> Maxim Shatskih, Windows DDK MVP
> StorageCraft Corporation
> xxxxx@storagecraft.com
> http://www.storagecraft.com
>
>
> ----- Original Message -----
> From: “Avinash Kumar”
> To: “Windows File Systems Devs Interest List”
> Sent: Thursday, February 05, 2004 1:12 AM
> Subject: [ntfsd] How to get the system env variables inside a driver.
>
>
> > Hi,
> >
> > I want to get the system environment variables like SystemRoot,
> > SystemDrive etc inside my driver.
> >
> > How can I get it. Is it a well defined value or there is some call
> > to get it.
> >
> > Regards,
> > Avinash
> >
> > —
> > Questions? First check the IFS FAQ at
> https://www.osronline.com/article.cfm?id=17
> >
> > You are currently subscribed to ntfsd as: xxxxx@storagecraft.com To
> > unsubscribe send a blank email to xxxxx@lists.osr.com
> >
>
>
> —
> Questions? First check the IFS FAQ at
> https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: xxxxx@commvault.com To
> unsubscribe send a blank email to xxxxx@lists.osr.com
>
> —
> Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: xxxxx@storagecraft.com To
> unsubscribe send a blank email to xxxxx@lists.osr.com
>

—
Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

You are currently subscribed to ntfsd as: xxxxx@commvault.com To
unsubscribe send a blank email to xxxxx@lists.osr.com

6

How should I use the path(file name) to access a file “myfile” in system
root folder?

1 \systemroot\myfile ->I get a status C000003B

2 systemroot\myfile -> I get a status C000003B

3 ??\systemroot\myfile -> I get a status C000003A

4 ??%systemroot%\myfile -> I get a status C000003A

RtlInitUnicodeString(&fileName, deviceExtension->myFile);
InitializeObjectAttributes(&objectAttributes,
(PUNICODE_STRING)&fileName, OBJ_CASE_INSENSITIVE, NULL, NULL);

status=ZwCreateFile(&fileHandle, GENERIC_READ|SYNCHRONIZE,
&objectAttributes, &IoStatus,
0, FILE_ATTRIBUTE_NORMAL, FILE_SHARE_READ, FILE_OPEN,
FILE_SYNCHRONOUS_IO_NONALERT|FILE_NO_INTERMEDIATE_BUFFERING, NULL,
0);

Regards,
Avinash

-----Original Message-----
From: Maxim S. Shatskih [mailto:xxxxx@storagecraft.com]
Sent: Wednesday, February 04, 2004 6:00 PM
To: Windows File Systems Devs Interest List
Subject: Re: [ntfsd] How to get the system env variables inside a
driver.

It is a good design idea that all files accessed from the driver are
located under \SystemRoot.

Why not follow it?

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

----- Original Message -----
From: “Avinash Kumar”
To: “Windows File Systems Devs Interest List”
Sent: Thursday, February 05, 2004 1:36 AM
Subject: RE: [ntfsd] How to get the system env variables inside a
driver.

> Thanks Max,
>
> I wanted to use SystemDrive instead of SystemRoot to build my path
> information. Will that work? I’ll give that a try.
>
> Regards,
> Avinash
>
>
>
> -----Original Message-----
> From: Maxim S. Shatskih [mailto:xxxxx@storagecraft.com]
> Sent: Wednesday, February 04, 2004 5:25 PM
> To: Windows File Systems Devs Interest List
> Subject: Re: [ntfsd] How to get the system env variables inside a
> driver.
>
>
> For what?
>
> To access files in SystemRoot, just use the \SystemRoot\path
> pathname. It works for kernel code.
>
> Maxim Shatskih, Windows DDK MVP
> StorageCraft Corporation
> xxxxx@storagecraft.com
> http://www.storagecraft.com
>
>
> ----- Original Message -----
> From: “Avinash Kumar”
> To: “Windows File Systems Devs Interest List”
> Sent: Thursday, February 05, 2004 1:12 AM
> Subject: [ntfsd] How to get the system env variables inside a driver.
>
>
> > Hi,
> >
> > I want to get the system environment variables like SystemRoot,
> > SystemDrive etc inside my driver.
> >
> > How can I get it. Is it a well defined value or there is some call
> > to get it.
> >
> > Regards,
> > Avinash
> >
> > —
> > Questions? First check the IFS FAQ at
> https://www.osronline.com/article.cfm?id=17
> >
> > You are currently subscribed to ntfsd as: xxxxx@storagecraft.com To
> > unsubscribe send a blank email to xxxxx@lists.osr.com
> >
>
>
> —
> Questions? First check the IFS FAQ at
> https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: xxxxx@commvault.com To
> unsubscribe send a blank email to xxxxx@lists.osr.com
>
> —
> Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: xxxxx@storagecraft.com To
> unsubscribe send a blank email to xxxxx@lists.osr.com
>

—
Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

You are currently subscribed to ntfsd as: xxxxx@commvault.com To
unsubscribe send a blank email to xxxxx@lists.osr.com

7

> 1 \systemroot\myfile ->I get a status C000003B

This must work.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

8

> ----------

From: xxxxx@storagecraft.com[SMTP:xxxxx@storagecraft.com]
Reply To: xxxxx@lists.osr.com
Sent: Thursday, February 05, 2004 1:35 AM
To: xxxxx@lists.osr.com
Subject: Re: [ntfsd] How to get the system env variables inside a
driver.

> 1 \systemroot\myfile ->I get a status C000003B

This must work.

STATUS_OBJECT_PATH_SYNTAX_BAD… I’d check if all '' are doubled (sorry if
it is obvious).

Best regards,

Michal Vodicka
STMicroelectronics Design and Application s.r.o.
[michal.vodicka@st.com, http:://www.st.com]

9

You can check status returned by ZwCreateFile. I guess it is
STATUS_SHARING_VIOLATION. If it is the case you can try to supply different
SharedAccess or DesiredAccess to ZwCreateFile.
Alternatively you can open the file once at system startup and keep it
opened.

Alexei.

I am having this problem that if the file is opened by someone in
usermode ( even explorer ) my open is kernel fails. I am not sure why so
I felt let me keep it in system volume information where the chances are
very less for someone to browse/open.

Any idea why a Kmode File Open starts failing if someone opens it in the
user mode.

Regards,
Avinash

10

Yup I am taking care of it by having \ for each . One thing to mention
here. I am below the file system in the stack if that causes any issue
here.

Regards,
Avinash

-----Original Message-----
From: Vodicka, Michal [mailto:michal.vodicka@st.com]
Sent: Wednesday, February 04, 2004 7:51 PM
To: Windows File Systems Devs Interest List
Subject: RE: [ntfsd] How to get the system env variables inside a
driver.

From: xxxxx@storagecraft.com[SMTP:xxxxx@storagecraft.com]
Reply To: xxxxx@lists.osr.com
Sent: Thursday, February 05, 2004 1:35 AM
To: xxxxx@lists.osr.com
Subject: Re: [ntfsd] How to get the system env variables inside a
driver.

> 1 \systemroot\myfile ->I get a status C000003B

This must work.

STATUS_OBJECT_PATH_SYNTAX_BAD… I’d check if all '' are doubled (sorry
if it is obvious).

Best regards,

Michal Vodicka
STMicroelectronics Design and Application s.r.o. [michal.vodicka@st.com,
http:://www.st.com]

Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

You are currently subscribed to ntfsd as: xxxxx@commvault.com To
unsubscribe send a blank email to xxxxx@lists.osr.com