the full path name in device driver

[yanping wang]

IoCreateDevice's third parameter is DeviceName, while IoCreateSymbolicLink's first parameter is SymbolicLinkName. what is their full path name? I don't known the difference between "\\Device\\DrvFltIp","\\DosDevices\\DrvFltIp" or "\\??\\DrvFltIp"

[Anonymous]

Not quite a full answer, but here's code I use to work with a FILE_DEVICE_UNKNOWN device that just needs simple start/open/read/close ops. I use the following code to setup names for my device - "\\Device\\TestDriver4" is used to identify the device for the CreateService calls 'name of service' - (TestDriver4), while "\\DosDevices\\TDRV4" enables opening of the device with CreateFile as "\\.\TDRV4".

// internal device name - season to taste
#define TDRV4_INTERNAL_NAME L"\\Device\\TestDriver4"

// symbolic link name - seems to be necessary to use 'DosDevices'
// once in place (see call to IoCreateSymbolicLink in TDrv1_CreateDevice0)
// the CreateFile() API will be able to open our device as
// "\\\\.\\TDRV4" [ i.e. "\\.\TDRV4"]
#define TDRV4_SYMBOLICLINK_NAME L"\\DosDevices\\TDRV4"

In my drivers TDrv4_CreateDevice0 fn, the internal name is used in IoCreateDevice, and the symbolic name (aka file name) is used in the call to IoCreateSymbolicLink.

RtlInitUnicodeString( &ustrInternalName, TDRV4\_INTERNAL\_NAME);   

// create the device
result = IoCreateDevice( pDriverObj,                // From DriverEntry.

            sizeof(TDRV4\_DEVICE\_EXTENSION), // Make us a block of non-paged pool 
                                            // large enough to store our extension data.
                                    
            &ustrInternalName,      // Any device object that can be 
                                    // the target of an I/O request or 
                                    // that a higher-level driver can 
                                    // connect to must have a DeviceName. 
                                    // An unnamed device object is visible 
                                    // only to the driver that created it 
                                    // or to an FSD through a volume parameter block (VPB).
                                    // (ref \[NTDDK\])

            FILE\_DEVICE\_UNKNOWN,       // (We'd use FILE\_DEVICE\_SERIAL for a serial filter, e.g.)
            0,                         // DeviceCharacteristics ignored.
            FALSE,                     // Exclusive - if TRUE, thread IO calls serialized.
            &pDevObj);                 // On return, will hold pointer to the new device object.

if(NT\_SUCCESS(result)) {

    // stop chain
    pDevObj->NextDevice = NULL;
    pDevObj->AttachedDevice = NULL;

    ////