problems with calling IoCreateDevice in a dispatch routine

I have to create a new device inside a DispatchWrite routine. I know ,
correct me if im wrong, that i just have to create the device just like
i do in the DriverEntry function,but i just have to take care of the
IO_DEVICE_INITIALIZING bit flag. I do this, but very strange things
happen to me. at run time IoCreateDevice returns STATUS_SUCCESS, and
IoCreateSymbolicLink returns STATUS_SUCCESS too. But when i go to see
what Device name and what symbolic name exists in the system, i find
out there is just the device name, and not the symbolic name. very
strange, couse infact IoCreateSymbolicLink returns success.
I copy and paste my code here... I would really appreciate if someone
can take a look and find the way to help a poor student with a teacher
who thinks developing device drivers is easy

//this code is inside a myDispatchWrite routine

NTSTATUS status;
PDEVICE_OBJECT pDevObj;
PDEVICE_EXTENSION pDevExt;

// Form the internal Device Name
CUString devName("\\Device\\MyDevice");//this is just a class of W2000
device drivers books, is a class 4 unicode with overloaded operators

status =
IoCreateDevice( pDriverObject,//someone gives u pDriverObject
sizeof(DEVICE_EXTENSION),
&(UNICODE_STRING)devName, //another overloaded operator of CUString,
the unicode class of W2000 DD book
FILE_DEVICE_SERIAL_PORT ,
0, TRUE,
&pDevObj );
if (!NT_SUCCESS(status))
return status;

// Initialize the Device Extension code dont do much and is missing

pDevObj->Flags |= DO_BUFFERED_IO ; //i wanna do buffered io
// i dont set up the DEVICE_OBJECT::Stack field, is it correct?

// Form the symbolic link name
CUString symLinkName("\\??\\MyDEV");


// Now create the link name
status =
IoCreateSymbolicLink( &(UNICODE_STRING)symLinkName,
&(UNICODE_STRING)devName );
if (!NT_SUCCESS(status)) {
// if it fails now, must delete Device object
IoDeleteDevice( pDevObj );
return status;
}


pDevObj->Flags &= ~DO_DEVICE_INITIALIZING;// i tell to Io Manger i
finished with the device initialization

return STATUS_SUCCESS;

//END

the code is this... It executes... IoCreateDevice and
IoCreateSymbolicLink return STATUS_PERFECT_WONDELFUL_SUCCESS , but when
i launch my WinObj to c if there are the device name and the symbolic
name, the device name there is, the symbolic no... I dont think the
problem is in WinObj....

 

Well you might want to try a symlink name of "\\DosDevices\\MyDev" since
that is the convention for in the kernel. If that doesn't work dump the
C++ crap, since it is likely something in there.

 

Is it possible that the symlink gets created in the wrong namespace, i.e. in
the namespace of the current session, instead of the global namespace?

I would probably check with winobj (or similar tool) to see if the symlink
has been created under \\sessions\SOMETHING instead of \\global\.

Hope it helps
GV

 

Since the dispatch routine is running in the context of the user process,
the symbolic link you are creating ends up in the local session space of the
process. If you want the symbolic link to be visible to all the users then
you should create it in the global name by using \GLOBAL??\ prefix instead
of \??\.

So change your code from:

CUString symLinkName("\\??\\MyDEV");

to this and you will be set:

CUString symLinkName("\\GLOBAL??\\MyDEV");

-Eliyas

 

Thanks a lot Aliyas (and Gianluca too) ... the problem was exactly
this...

4 Gianluca... im italian too... but u do drivers 4 fun , or 4 job?...
and if it is for job, how do u c the career of drivers developer in
Italy? couse i (relatively) like developing device drivers , but im not
sure in Italy i can find such a job...