IWDFDevice2::CreateSymbolicLinkWithReferenceString method (wudfddi.h)

Article
10/21/2021

[Warning: UMDF 2 is the latest version of UMDF and supersedes UMDF 1. All new UMDF drivers should be written using UMDF 2. No new features are being added to UMDF 1 and there is limited support for UMDF 1 on newer versions of Windows 10. Universal Windows drivers must use UMDF 2. For more info, see Getting Started with UMDF.]

TheCreateSymbolicLinkWithReferenceString method creates a symbolic link name, and optionally, a reference string, for a device

Syntax

HRESULT CreateSymbolicLinkWithReferenceString(
  [in]           PCWSTR pSymbolicLink,
  [in, optional] PCWSTR pReferenceString
);

Parameters

[in] pSymbolicLink

A pointer to a NULL-terminated character string that becomes the user-visible name of the device. The symbolic link name must be in the global DosDevices namespace.

[in, optional] pReferenceString

A pointer to a NULL-terminated character string that Windows appends to the device name when an application uses the symbolic name that the pSymbolicLink parameter specifies. For more information, see the following Remarks section. This parameter is optional and can be NULL.

Return value

CreateSymbolicLinkWithReferenceString returns S_OK if the operation succeeds. Otherwise, the method might return one of the following values:

Return code	Description
E_INVALIDARG	The caller specified an invalid value for an input parameter.
E_OUTOFMEMORY	The memory allocation failed.

This method might return one of the other values that Winerror.h contains.

Remarks

CreateSymbolicLinkWithReferenceString creates a symbolic link name, and optionally a reference string, for the device that the IWDFDevice2 interface represents. After a driver calls CreateSymbolicLinkWithReferenceString, applications can use the symbolic link name to access the device.

Suppose your device's name is "\Device\MyDevice". You can create a symbolic link name of "DeviceUserName" for your device by specifying "L"DeviceUserName"" for the pSymbolicLink parameter. If you specify "L"Instance3"" for the pReferenceString parameter, you are creating a symbolic link to \Device\MyDevice\Instance3. If an application opens the device by using the symbolic link name, the I/O manager opens \Device\MyDevice and creates a WDM file object that contains the \Instance3 string as the file name. Your UMDF-based driver receives a framework-created file object, which also contains the \Instance3 string as the file name (see IWDFFile::RetrieveFileName).

Typically, instead of providing symbolic links, framework-based drivers provide device interfaces that applications can use to access their devices.

If the device is removed unexpectedly (surprise-removed), the framework removes the symbolic link to the device. The driver can then use the symbolic link name for a new instance of the device.

If you do not need to add a reference string to your device's symbolic link name, your driver can call IWDFDevice::CreateSymbolicLink instead of CreateSymbolicLinkWithReferenceString.

Examples

The following line defines a symbolic link name prefix in the global DosDevices namespace.

#define SYMBOLIC_LINK_NAME_PREFIX   L"\\DosDevices\\Global\\"

The following code example creates a symbolic name string, obtains the IWDFDevice2 interface, and then calls CreateSymbolicLinkWithReferenceString.


    IWDFDevice2 *pDevice2 = NULL;
    HRESULT hr;

    //
    // Create symbolic link name string.
    //
    hr = StringCchPrintf(portFullName,
                         portFullNameLength,
                         L"%ws%ws",
                         SYMBOLIC_LINK_NAME_PREFIX,
                         portName);
    if (FAILED(hr))
    {
        goto Exit;
    }

    //
    // Get a pointer to the IWDFDevice2 interface.
    //
    hr = pIWDFDevice->QueryInterface(__uuidof(IWDFDevice2),
                                     (void**) &pDevice2);
    if (SUCCEEDED(hr)) 
    {
    hr = pDevice2->CreateSymbolicLinkWithReferenceString(portFullName,
                                                         portCountString);
    if (FAILED(hr))
        {
            goto Exit;
        }
        SAFE_RELEASE(pDevice2);
    }

Requirements

Requirement	Value
End of support	Unavailable in UMDF 2.0 and later.
Target Platform	Desktop
Minimum UMDF version	1.9
Header	wudfddi.h (include Wudfddi.h)
DLL	WUDFx.dll

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