Enumerating Current Devices

Applications can use the SetupDiGetClassDevsEx function to retrieve the list of current devices. The following example function demonstrates how to retrieve this list.

HDEVINFO DoDeviceEnum( GUID InterfaceClassGuid 
)
/*
Routine Description:
    Retrieves the device information set that contains that contains
    the devices of the specified class. 

Parameters:
    InterfaceClassGuid - The interface class GUID. 

Return Value:
    If the function succeeds, the return value is a handle to the 
    device information set.

    If the function fails, the return value is zero.
*/
{
    HDEVINFO DeviceInfoSet;
    HDEVINFO NewDeviceInfoSet;

    // Create a device information set that will be the container for 
    // the device interfaces.

    DeviceInfoSet = SetupDiCreateDeviceInfoList(NULL, NULL);
    
    if(DeviceInfoSet == INVALID_HANDLE_VALUE) {
        Err = GetLastError();
        printf( "SetupDiCreateDeviceInfoList failed: %lx.\n", Err );
        return 0;
    }

    // Retrieve the device information set for the interface class.

    NewDeviceInfoSet = SetupDiGetClassDevsEx( InterfaceClassGuid,
        NULL,
        NULL,
        DIGCF_PRESENT | DIGCF_DEVICEINTERFACE,
        DeviceInfoSet,
        NULL,
        NULL
    );

    if(NewDeviceInfoSet == INVALID_HANDLE_VALUE) 
    {
        Err = GetLastError();
        printf( "SetupDiGetClassDevsEx failed: %lx.\n", Err );
        return 0;
    }

    return NewDeviceInfoSet;
}

After you have registered to receive device interface notification messages, you can call this function to obtain a device information set that contains the current list of device interfaces. When you receive a DBT_DEVICEARRIVAL event, you can use the SetupDiOpenDeviceInterface function to add the device interface to the device information set. When you receive a DBT_DEVICEREMOVECOMPLETE event, you can use the SetupDiDeleteDeviceInterfaceData function to delete the device interface from the device information set.