在驱动里从注册表里读写参数

摘自ramdisk驱动程序

VOID
RamDiskQueryDebugRegParameters(
    IN PUNICODE_STRING RegistryPath
    )
/*++

Routine Description:

    This routine is called from the DriverEntry to get the debug
    parameters from the registry. If the registry query fails, then
    default values are used.

Arguments:

    RegistryPath    - Points the service path to get the registry parameters

Return Value:

    None

--*/
{

    RTL_QUERY_REGISTRY_TABLE    rtlQueryRegTbl[ 4 + 1 ];  // Need 1 for NULL
    NTSTATUS                    status;
    DEBUG_INFO                  defDebugRegInfo;

    PAGED_CODE();

    DBGPRINT( DBG_COMP_INIT, DBG_LEVEL_VERBOSE, ("QueryDebugRegParameters\n" ) );
    ASSERT( RegistryPath->Buffer != NULL );

    // Set the default values

    defDebugRegInfo.BreakOnEntry      = DEFAULT_BREAK_ON_ENTRY;
    defDebugRegInfo.DebugLevel        = DEFAULT_DEBUG_LEVEL;
    defDebugRegInfo.DebugComp         = DEFAULT_DEBUG_COMP;

    RtlZeroMemory( rtlQueryRegTbl, sizeof(rtlQueryRegTbl) );

    //
    // Setup the query table
    //

    rtlQueryRegTbl[0].Flags         = RTL_QUERY_REGISTRY_SUBKEY;
    rtlQueryRegTbl[0].Name          = L"Parameters";
    rtlQueryRegTbl[0].EntryContext  = NULL;
    rtlQueryRegTbl[0].DefaultType   = (ULONG)NULL;
    rtlQueryRegTbl[0].DefaultData   = NULL;
    rtlQueryRegTbl[0].DefaultLength = (ULONG)NULL;

    //
    // Debug paramters
    //

    rtlQueryRegTbl[1].Flags         = RTL_QUERY_REGISTRY_DIRECT;
    rtlQueryRegTbl[1].Name          = L"BreakOnEntry";
    rtlQueryRegTbl[1].EntryContext  = &BreakOnEntry;
    rtlQueryRegTbl[1].DefaultType   = REG_DWORD;
    rtlQueryRegTbl[1].DefaultData   = &defDebugRegInfo.BreakOnEntry;
    rtlQueryRegTbl[1].DefaultLength = sizeof(ULONG);

    rtlQueryRegTbl[2].Flags         = RTL_QUERY_REGISTRY_DIRECT;
    rtlQueryRegTbl[2].Name          = L"DebugLevel";
    rtlQueryRegTbl[2].EntryContext  = &DbgLevel;
    rtlQueryRegTbl[2].DefaultType   = REG_DWORD;
    rtlQueryRegTbl[2].DefaultData   = &defDebugRegInfo.DebugLevel;
    rtlQueryRegTbl[2].DefaultLength = sizeof(ULONG);

    rtlQueryRegTbl[3].Flags         = RTL_QUERY_REGISTRY_DIRECT;
    rtlQueryRegTbl[3].Name          = L"DebugComp";
    rtlQueryRegTbl[3].EntryContext  = &DbgComp;
    rtlQueryRegTbl[3].DefaultType   = REG_DWORD;
    rtlQueryRegTbl[3].DefaultData   = &defDebugRegInfo.DebugComp;
    rtlQueryRegTbl[3].DefaultLength = sizeof(ULONG);

    status = RtlQueryRegistryValues(
                                    RTL_REGISTRY_ABSOLUTE | RTL_REGISTRY_OPTIONAL,    
                                    RegistryPath->Buffer,
                                    rtlQueryRegTbl,
                                    NULL,
                                    NULL
                                    );

    if ( !NT_SUCCESS( status ) ) {
        DBGPRINT( DBG_COMP_INIT, DBG_LEVEL_WARN, ("RrlQueryRegistryValues returned 0x%x\n", status ) );
        BreakOnEntry = defDebugRegInfo.BreakOnEntry;
        DbgLevel     = defDebugRegInfo.DebugLevel;
        DbgComp      = defDebugRegInfo.DebugComp;
    }
    DBGPRINT( DBG_COMP_INIT, DBG_LEVEL_INFO, ("BreakOnEntry = 0x%lx\n", BreakOnEntry) );
    DBGPRINT( DBG_COMP_INIT, DBG_LEVEL_INFO, ("DebugLevel   = 0x%lx\n", DbgLevel) );
    DBGPRINT( DBG_COMP_INIT, DBG_LEVEL_INFO, ("DebugComp    = 0x%lx\n", DbgComp) );
    return;
}   // End of RamDiskDebugQueryRegParameters()