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sending IRP_MJ_PNP to \device\harddisk0\partition0 with minor function IRP_MN_QUERY_DEVICE_RELATIONS

Liam__hkLiam__hk Member Posts: 1
edited November 2020 in NTDEV

I was reading about file system stack and found a source code and i am trying to understand what it is actually doing

it is finding the device object of \device\harddisk0\partition0 and then it sends a IRP_MJ_PNP request to it and builds the IRP using IoBuildSynchronousFsdRequest, sets the minorfunc to IRP_MN_QUERY_DEVICE_RELATIONS and QueryDeviceRelations.Type to TargetDeviceRelation

now can someone explain what does this actually do? whats the purpose of IRP_MN_QUERY_DEVICE_RELATIONS regarding the partition0 device object and whats the deal with this TargetDeviceRelation? where can i read more about this?

    KeInitializeEvent( &event, NotificationEvent, FALSE );

    irp = IoBuildSynchronousFsdRequest( IRP_MJ_PNP,
                                        &ioStatusBlock );

    if (irp == NULL) {
        goto End;

    irpStack = IoGetNextIrpStackLocation( irp );
    irpStack->MinorFunction = IRP_MN_QUERY_DEVICE_RELATIONS;
    irpStack->Parameters.QueryDeviceRelations.Type = TargetDeviceRelation;

    irp->IoStatus.Status = STATUS_NOT_SUPPORTED ;

    status = IoCallDriver( DeviceObject, irp );

    if (status == STATUS_PENDING) {

        KeWaitForSingleObject( &event, Executive, KernelMode, FALSE, NULL );
        status = ioStatusBlock.Status;}


  • Tim_RobertsTim_Roberts Member - All Emails Posts: 13,768
    edited November 2020

    where can i read more about this?

    How can you ask that question with a straight face? I Googled for IRP_MN_QUERY_DEVICE_RELATIONS, and the top hit was the MSDN page that describes these option. TargetDeviceRelations returns the device object associated with a particular file object.

    Tim Roberts, [email protected]
    Providenza & Boekelheide, Inc.

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