WdfRegistryQueryString function (wdfregistry.h)

Article
04/18/2022

[Applies to KMDF and UMDF]

The WdfRegistryQueryString method retrieves the string data that is currently assigned to a specified registry string value and assigns the string to a specified framework string object.

Syntax

NTSTATUS WdfRegistryQueryString(
  [in] WDFKEY           Key,
  [in] PCUNICODE_STRING ValueName,
  [in] WDFSTRING        String
);

Parameters

[in] Key

A handle to a registry-key object that represents an opened registry key.

[in] ValueName

A pointer to a UNICODE_STRING structure that contains a name for the registry value.

[in] String

A handle to a framework string object. The framework will assign the registry value's string data to this object.

Return value

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

Return code	Description
STATUS_INVALID_DEVICE_REQUEST	WdfRegistryQueryString was not called at IRQL = PASSIVE_LEVEL.
STATUS_INVALID_PARAMETER	An invalid parameter was specified.
STATUS_INSUFFICIENT_RESOURCES	There was insufficient memory to complete the operation.
STATUS_ACCESS_DENIED	The driver did not open the registry key with KEY_QUERY_VALUE, KEY_READ, or KEY_ALL_ACCESS access.
STATUS_OBJECT_TYPE_MISMATCH	The data type of the registry value that the ValueName parameter specified was not REG_SZ.
STATUS_OBJECT_NAME_NOT_FOUND	The registry value was not available.
STATUS_RESOURCE_DATA_NOT_FOUND	The registry value exists under the specified key, but is empty.

For a list of other return values that the WdfRegistryQueryString method might return, see Framework Object Creation Errors.

This method also might return other NTSTATUS values.

A bug check occurs if the driver supplies an invalid object handle.

Remarks

To obtain a string from a string object, your driver can call WdfStringGetUnicodeString.

For more information about registry-key objects, see Using the Registry in Framework-Based Drivers.

Examples

The following code example creates a string object, retrieves string data from a registry key, and obtains the string data from the string object.

UNICODE_STRING str;
WDFSTRING string;
NTSTATUS status;
DECLARE_CONST_UNICODE_STRING(valueName, STRING_VALUE_NAME);

status = WdfStringCreate(
                         NULL,
                         WDF_NO_OBJECT_ATTRIBUTES,
                         &string
                         );
if (NT_SUCCESS(status)) {
    status = WdfRegistryQueryString(
                                    Key, 
                                    &valueName,
                                    string
                                    );
    if (NT_SUCCESS(status)) {
        WdfStringGetUnicodeString(
                                  string,
                                  &str
                                  );
    }
}

Requirements

Requirement	Value
Target Platform	Universal
Minimum KMDF version	1.0
Minimum UMDF version	2.0
Header	wdfregistry.h (include Wdf.h)
Library	Wdf01000.sys (KMDF); WUDFx02000.dll (UMDF)
IRQL	PASSIVE_LEVEL
DDI compliance rules	DriverCreate(kmdf), KmdfIrql(kmdf), KmdfIrql2(kmdf), KmdfIrqlExplicit(kmdf)