ZwEnumerateValueKey function (wdm.h)

Article
01/13/2023

The ZwEnumerateValueKey routine gets information about the value entries of an open key.

Syntax

NTSYSAPI NTSTATUS ZwEnumerateValueKey(
  [in]            HANDLE                      KeyHandle,
  [in]            ULONG                       Index,
  [in]            KEY_VALUE_INFORMATION_CLASS KeyValueInformationClass,
  [out, optional] PVOID                       KeyValueInformation,
  [in]            ULONG                       Length,
  [out]           PULONG                      ResultLength
);

Parameters

[in] KeyHandle

Handle to the registry key that you want to enumerate value entries for. A successful call to ZwCreateKey or ZwOpenKey creates this handle.

[in] Index

The zero-based index of the subkey that you want value information for.

[in] KeyValueInformationClass

Specifies a KEY_VALUE_INFORMATION_CLASS value that determines the type of information returned in the KeyValueInformation buffer.

[out, optional] KeyValueInformation

Pointer to a caller-allocated buffer that receives the requested information.

[in] Length

Specifies the size, in bytes, of the KeyValueInformation buffer.

[out] ResultLength

Pointer to a variable that receives the size, in bytes, of the value information. If this routine returns STATUS_SUCCESS, the variable indicates the amount of data returned. If this routine returns STATUS_BUFFER_OVERFLOW or STATUS_BUFFER_TOO_SMALL, the variable indicates the buffer size that is required to hold the value information.

Return value

ZwEnumerateValueKey returns STATUS_SUCCESS on success, or the appropriate error code on failure. Possible error code values include:

Return code	Description
STATUS_BUFFER_OVERFLOW	The buffer supplied is too small, and only partial data has been written to the buffer. *ResultLength is set to the minimum size required to hold the requested information.
STATUS_BUFFER_TOO_SMALL	The buffer supplied is too small, and no data has been written to the buffer. *ResultLength is set to the minimum size required to hold the requested information.
STATUS_INVALID_PARAMETER	The KeyInformationClass parameter is not a valid KEY_VALUE_INFORMATION_CLASS value.
STATUS_NO_MORE_ENTRIES	The Index value is out of range for the registry key specified by KeyHandle. For example, if a key has n subkeys, then for any value greater than n-1 the routine returns STATUS_NO_MORE_ENTRIES.

Remarks

The KeyHandle passed to ZwEnumerateValueKey must have been opened with KEY_QUERY_VALUE access. This is accomplished by passing KEY_QUERY_VALUE, KEY_READ, or KEY_ALL_ACCESS as the DesiredAccess parameter to ZwCreateKey or ZwOpenKey.

The Index is simply a way to select among subkeys with value entries. Two calls to ZwEnumerateValueKey with the same Index are not guaranteed to return the same results.

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 "NtEnumerateValueKey" instead of "ZwEnumerateValueKey".

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)