WdfRegistryQueryValue - NtDoc
Native API online documentation, based on the System Informer
(formerly Process Hacker) phnt
headers
// wdfregistry.h
NTSTATUS WdfRegistryQueryValue(
[in] WDFKEY Key,
[in] PCUNICODE_STRING ValueName,
[in] ULONG ValueLength,
[out, optional] PVOID Value,
[out, optional] PULONG ValueLengthQueried,
[out, optional] PULONG ValueType
);
View the official Windows Driver Kit DDI referenceNo description available.
[Applies to KMDF and UMDF]
The WdfRegistryQueryValue method retrieves the data that is currently assigned to a specified registry value.
Key [in]A handle to a registry-key object that represents an opened registry key.
ValueName [in]A pointer to a UNICODE_STRING structure that contains a value name.
ValueLength [in]The length, in bytes, of the buffer that Value points to.
Value [out, optional]A pointer to a driver-allocated buffer that receives the registry value's data. If this pointer is NULL, WdfRegistryQueryValue retrieves the data length but not the data.
ValueLengthQueried [out, optional]A pointer to a location that receives the registry value's data length. This pointer is optional and can be NULL.
ValueType [out, optional]A pointer to a location that receives the registry value's data type. For a list of data type values, see the Type member of KEY_VALUE_BASIC_INFORMATION. This pointer is optional and can be NULL.
WdfRegistryQueryValue returns STATUS_SUCCESS if the operation succeeds. Otherwise, the method might return one of the following values:
| Return code | Description |
|---|---|
| STATUS_INVALID_DEVICE_REQUEST | WdfRegistryQueryValue was not called at IRQL = PASSIVE_LEVEL. |
| STATUS_INVALID_PARAMETER | An invalid parameter was specified. |
| STATUS_ACCESS_DENIED | The driver did not open the registry key with KEY_QUERY_VALUE, KEY_READ, or KEY_ALL_ACCESS access. |
| STATUS_BUFFER_OVERFLOW | The buffer that the Value parameter points to is too small, and only partial data has been written to the buffer. |
| STATUS_BUFFER_OVERFLOW | The Value buffer is too small, and no data has been written to the buffer. |
| STATUS_OBJECT_NAME_NOT_FOUND | The registry value was not available. |
This method also might return other NTSTATUS values.
A bug check occurs if the driver supplies an invalid object handle.
For more information about registry-key objects, see Using the Registry in Framework-Based Drivers.
The following code example opens a device's hardware key and retrieves the data that is assigned to the NumberOfToasters value, which is stored under the device's hardware key.
WCHAR comPort[FM_COM_PORT_STRING_LENGTH];
ULONG length;
NTSTATUS status;
ULONG length, valueType, value;
DECLARE_CONST_UNICODE_STRING(valueName, L"NumberOfToasters");
WDFKEY hKey;
status = WdfDeviceOpenRegistryKey(
Device,
PLUGPLAY_REGKEY_DEVICE,
KEY_QUERY_VALUE,
NULL,
&hKey
);
if (!NT_SUCCESS (status)) {
goto Error;
}
status = WdfRegistryQueryValue(
hKey,
&valueName,
sizeof(ULONG),
&value,
&length,
&valueType
);