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From: Slava Monich <monich@ftp.com>
Newsgroups: comp.os.ms-windows.programmer.nt.kernel-mode
Subject: Re: Retrieve name of a device object
Date: Sat, 01 Nov 1997 01:00:05 -0500
Organization: FTP Software, Inc.
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To: Mark van Velsen <mvelsen@iaehv.nl>

Mark van Velsen wrote:
> 
> one of the undocumented ones... Looking into ntoskrnl.exe I noticed
> that this function has 4 parameters, probably looking sometime like:
> 
> NTSTATUS ObQueryNameString(
>         IN PVOID Object,
>         IN PUNICODE_STRING Name,
>         IN POBJECT_TYPE ObjectType,
>         ?? );
> 
> Anyone an idea?
> 

I have a slightly different interpretation of 
ObQueryNameString:

NTSTATUS
ObQueryNameString(
    PVOID  Object,
    POBJECT_NAME_INFORMATION Info,
    ULONG  Length,
    PULONG ReturnLength);

OBJECT_NAME_INFORMATION is (accidentally?) defined in NTDDK.H 
and is actually a UNICODE_STRING:

typedef struct _OBJECT_NAME_INFORMATION {
    UNICODE_STRING Name;
} OBJECT_NAME_INFORMATION, *POBJECT_NAME_INFORMATION;

Given a device object, this function seems to return its
original device name (even though the device may be opened 
through a symbolic link). At least I was able to translate 
a COM port device object into \Device\SerialX name. The code 
looked like this:

char Buffer[256];
NTSTATUS ObStatus;
ULONG ReturnLength = 0;
OBJECT_NAME_INFORMATION * Info = (OBJECT_NAME_INFORMATION *)Buffer;
RtlZeroMemory(Info, sizeof(OBJECT_NAME_INFORMATION));
ObStatus = ObQueryNameString( Port->FileObject->DeviceObject,
                              Info, sizeof(Buffer),
                              &ReturnLength);
if ( NT_SUCCESS(ObStatus) && ReturnLength )
    if ( Info->Name.Length && Info->Name.Buffer )
    {
        TRACE1("Device: %wZ\n",&Info->Name);
        ..........
    }

Regards,
-Slava