ZwSetValueKey function (wdm.h)

Article
02/28/2023

The ZwSetValueKey routine creates or replaces a registry key's value entry.

Syntax

NTSYSAPI NTSTATUS ZwSetValueKey(
  [in]           HANDLE          KeyHandle,
  [in]           PUNICODE_STRING ValueName,
  [in, optional] ULONG           TitleIndex,
  [in]           ULONG           Type,
  [in, optional] PVOID           Data,
  [in]           ULONG           DataSize
);

Parameters

[in] KeyHandle

Handle to the registry key to write a value entry for. This handle is created by a successful call to ZwCreateKey or ZwOpenKey.

[in] ValueName

Pointer to the name of the value entry for which the data is to be written. This parameter can be a NULL pointer if the value entry has no name. If a name string is specified and the given name is not unique relative to its containing key, the data for an existing value entry is replaced.

[in, optional] TitleIndex

This parameter is reserved. Device and intermediate drivers should set this parameter to zero.

[in] Type

One of the following system-defined types of data to write:

Type value	Meaning
REG_BINARY	Binary data in any form.
REG_DWORD	A 4-byte numerical value.
REG_DWORD_LITTLE_ENDIAN	A 4-byte numerical value with the least significant byte at the lowest address. Identical to REG_DWORD.
REG_DWORD_BIG_ENDIAN	A 4-byte numerical value with the least significant byte at the highest address.
REG_EXPAND_SZ	A null-terminated Unicode string that contains unexpanded references to environment variables, such as "%PATH%".
REG_LINK	A Unicode string that names a symbolic link. This type is irrelevant to device and intermediate drivers.
REG_MULTI_SZ	An array of null-terminated strings, terminated by another zero.
REG_NONE	Data with no particular type.
REG_SZ	A null-terminated Unicode string.
REG_RESOURCE_LIST	A device driver's list of hardware resources, used by the driver or one of the physical devices it controls, in the \ResourceMap tree
REG_RESOURCE_REQUIREMENTS_LIST	A device driver's list of possible hardware resources it or one of the physical devices it controls can use, from which the system writes a subset into the \ResourceMap tree
REG_FULL_RESOURCE_DESCRIPTOR	A list of hardware resources that a physical device is using, detected and written into the \HardwareDescription tree by the system

Device drivers should not attempt to call ZwSetValueKey to explicitly write value entries in a subkey of the \Registry...\ResourceMap key. Only the system can write value entries to the \Registry...\HardwareDescription tree.

[in, optional] Data

Pointer to a caller-allocated buffer that contains the data for the value entry.

[in] DataSize

Specifies the size, in bytes, of the Data buffer. If Type is REG_XXX_SZ, this value must include space for any terminating zeros.

Return value

ZwSetValueKey returns STATUS_SUCCESS if the operation succeeds. Otherwise, this routine might return one of the following values:

Return code	Description
STATUS_ACCESS_DENIED	The caller does not have appropriate access to the registry value.
STATUS_INVALID_HANDLE	The handle is invalid.

Remarks

The KeyHandle passed to ZwSetValueKey must have been opened with the KEY_SET_VALUE DesiredAccess flag set for this call to succeed. For a description of possible values for DesiredAccess, see ZwCreateKey.

If the given key has no existing value entry with a name matching the given ValueName, ZwSetValueKey creates a new value entry with the given name. If a matching value entry name exists, this routine overwrites the original value entry for the given ValueName. Thus, ZwSetValueKey preserves a unique name for each value entry of any particular key. While each value entry name must be unique to its containing key, many different keys in the registry can have value entries with the same names.

For more information about working with registry keys, see Using the Registry in a Driver.

If the call to this function occurs in user mode, you should use the name "NtSetValueKey" instead of "ZwSetValueKey".

For calls from kernel-mode drivers, the NtXxx and ZwXxx versions of a Windows Native System Services routine can behave differently in the way that they handle and interpret input parameters. For more information about the relationship between the NtXxx and ZwXxx versions of a routine, see Using Nt and Zw Versions of the Native System Services Routines.

Requirements

Requirement	Value
Target Platform	Universal
Header	wdm.h (include Wdm.h, Ntddk.h, Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	PASSIVE_LEVEL
DDI compliance rules	HwStorPortProhibitedDDIs(storport), IrqlZwPassive(wdm), PowerIrpDDis(wdm), ZwRegistryCreate(storport), ZwRegistryCreate(storport), ZwRegistryCreate(wdm), ZwRegistryOpen(storport), ZwRegistryOpen(storport), ZwRegistryOpen(wdm)