ZwOpenKeyTransactedEx function

The ZwOpenKeyTransactedEx routine opens an existing registry key and associates the key with a transaction.


  PHANDLE            KeyHandle,
  ACCESS_MASK        DesiredAccess,
  POBJECT_ATTRIBUTES ObjectAttributes,
  ULONG              OpenOptions,
  HANDLE             TransactionHandle



A pointer to a HANDLE variable into which the routine writes the handle to the key.


Specifies the type of access to the key that the caller requests. This parameter is an ACCESS_MASK value. For more information, see the description of the DesiredAccess parameter of the ZwCreateKey routine.


A pointer to the object attributes of the key being opened. This parameter points to an OBJECT_ATTRIBUTES structure that must have been previously initialized by the InitializeObjectAttributes routine. The caller must specify the name of the registry key as the ObjectName parameter in the call to InitializeObjectAttributes. If the caller is not running in a system thread context, it must set the OBJ_KERNEL_HANDLE attribute when it calls InitializeObjectAttributes.


Specifies the options to apply when opening the key. Set this parameter to zero or to the bitwise OR of one or more of the following REG_OPTION_XXX flag bits.

OpenOptions flag Description
REG_OPTION_OPEN_LINK The key is a symbolic link. This flag is not used by device and intermediate drivers.
REG_OPTION_BACKUP_RESTORE The key should be opened with special privileges that allow backup and restore operations. This flag is not used by device and intermediate drivers.


A handle to a transaction object. To obtain this handle, you can call the ZwCreateTransaction routine. Or, if you have a pointer to a transaction object, you can supply the pointer to the ObOpenObjectByPointer routine to obtain the corresponding transaction handle.

Return Value

ZwOpenKeyTransactedEx returns STATUS_SUCCESS if the call successfully opens the key. Possible error return values include the following:

Return code Description
The ObjectAttributes parameter is NULL or points to invalid information.
The OpenOptions parameter value specifies invalid options.
The registry path in the object attributes is invalid.
The registry path in the object attributes was not found.
The caller did not have the required access rights to open a handle for the named registry key.
A memory allocation operation failed.


This routine provides a handle with which the caller can access a registry key. Additionally, this routine associates the key with an active transaction.

After the handle that is pointed to by KeyHandle is no longer being used, the driver must call the ZwClose routine to close it.

If the specified key does not exist in the registry, ZwOpenKeyTransactedEx returns an error status value and does not supply a key handle. Unlike the ZwCreateKeyTransacted routine, the ZwOpenKeyTransactedEx routine does not create the specified key if the key does not exist. Both ZwCreateKeyTransacted and ZwOpenKeyTransactedEx associate a registry key with a transaction.

The ZwOpenKeyEx routine is similar to ZwOpenKeyTransactedEx, but does not associate a key with a transaction.

The ZwOpenKeyTransacted routine is similar to ZwOpenKeyTransactedEx but does not accept an OpenOptions parameter. The OpenOptions parameter of ZwOpenKeyTransactedEx enables the caller to open a key that is a symbolic link, or to open a key for backup and restore operations. A call to ZwOpenKeyTransactedEx with OpenOptions parameter set to zero is equivalent to a call to ZwOpenKeyTransacted.

After a kernel-mode driver obtains a handle to a transaction (for example, by calling ZwCreateTransaction), the driver can perform a series of registry operations that are part of this transaction. The driver can close the transaction either by committing to the changes that were made in the transaction or by rolling back the transaction.

After the driver successfully completes all registry operations that are part of a transaction, it can call the ZwCommitTransaction routine to commit to the changes. The driver can call the ZwRollbackTransaction routine to roll back the transaction.

During a transaction, a registry operation is part of the transaction if the system call that performs the operation meets either of the following conditions:

  • The call specifies, as an input parameter, the transaction handle. For example, calls to ZwCreateKeyTransacted and ZwOpenKeyTransactedEx can associate one or more keys with the transaction.
  • The call specifies, as an input parameter, a registry key handle that was obtained by a call to ZwCreateKeyTransacted or ZwOpenKeyTransactedEx to which the transaction handle was supplied. For example, a call to the ZwSetValueKey routine can use a key handle that was obtained in this way to set the value of a registry key as part of a transaction.
For more information about kernel-mode transactions, see Using Kernel Transaction Manager.

ZwOpenKeyTransactedEx ignores the security information in the structure that the ObjectAttributes parameter points to.

If the kernel-mode caller is not running in a system thread context, it must ensure that any handles it creates are kernel handles. Otherwise, the handle can be accessed by the process in whose context the driver is running. For more information, see Object Handles.

For more information about how to work with registry keys in kernel mode, see Using the Registry in a Driver.


Minimum supported client Available in Windows 7 and later versions of the Windows operating system.
Target Platform Universal
Header wdm.h (include Wdm.h, Ntddk.h, Ntifs.h)
Library NtosKrnl.lib
DLL NtosKrnl.exe
DDI compliance rules PowerIrpDDis, HwStorPortProhibitedDDIs

See Also