NtQueryKey - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers 
#ifndef _NTREGAPI_H

/**
 * Queries information about a registry key.
 *
 * \param[in] KeyHandle A handle to the key to be queried.
 * \param[in] KeyInformationClass The type of information to be queried.
 * \param[out] KeyInformation A pointer to a buffer that receives the key information.
 * \param[in] Length The size of the buffer.
 * \param[out] ResultLength A pointer to a variable that receives the size of the data returned.
 * \return NTSTATUS Successful or errant status.
 */
NTSYSCALLAPI
NTSTATUS
NTAPI
NtQueryKey(
    _In_ HANDLE KeyHandle,
    _In_ KEY_INFORMATION_CLASS KeyInformationClass,
    _Out_writes_bytes_to_opt_(Length, *ResultLength) PVOID KeyInformation,
    _In_ ULONG Length,
    _Out_ PULONG ResultLength
    );

#endif

View code on GitHub
#ifndef _NTZWAPI_H

NTSYSCALLAPI
NTSTATUS
NTAPI
ZwQueryKey(
    _In_ HANDLE KeyHandle,
    _In_ KEY_INFORMATION_CLASS KeyInformationClass,
    _Out_writes_bytes_to_opt_(Length, *ResultLength) PVOID KeyInformation,
    _In_ ULONG Length,
    _Out_ PULONG ResultLength
    );

#endif

View code on GitHub
// wdm.h

NTSYSAPI NTSTATUS ZwQueryKey(
  [in]            HANDLE                KeyHandle,
  [in]            KEY_INFORMATION_CLASS KeyInformationClass,
  [out, optional] PVOID                 KeyInformation,
  [in]            ULONG                 Length,
  [out]           PULONG                ResultLength
);
View the official Windows Driver Kit DDI reference

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Windows Driver Kit DDI reference (nf-wdm-zwquerykey)

Description

The ZwQueryKey routine provides information about the class of a registry key, and the number and sizes of its subkeys.

Parameters

KeyHandle [in]

Handle to the registry key to obtain information about. This handle is created by a successful call to ZwCreateKey or ZwOpenKey.

KeyInformationClass [in]

Specifies a KEY_INFORMATION_CLASS value that determines the type of information returned in the KeyInformation buffer.

KeyInformation [out, optional]

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

Length [in]

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

ResultLength [out]

Pointer to a variable that receives the size, in bytes, of the requested key information. If ZwQueryKey returns STATUS_SUCCESS, the variable contains the amount of data returned. If ZwQueryKey returns STATUS_BUFFER_OVERFLOW or STATUS_BUFFER_TOO_SMALL, you can use the value of the variable to determine the required buffer size.

Return value

ZwQueryKey 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_INFORMATION_CLASS value.

Remarks

The KeyHandle passed to ZwQueryKey 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.

If KeyInformationClass is KeyNameInformation or KeyHandleTagsInformation, the KEY_QUERY_VALUE requirement does not apply.

ZwQueryKey can be used to obtain information that you can use to allocate buffers to hold registry data, such as the maximum size of a key's value entries or subkey names, or the number of subkeys. For example, you can call ZwQueryKey, use the returned information to allocate a buffer for a subkey, call ZwEnumerateKey to get the name of the subkey, and pass that name to an RtlXxxRegistry routine.

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 "NtQueryKey" instead of "ZwQueryKey".

For calls from kernel-mode drivers, the Nt*Xxx* and Zw*Xxx* 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 Nt*Xxx* and Zw*Xxx* versions of a routine, see Using Nt and Zw Versions of the Native System Services Routines.

See also

KEY_BASIC_INFORMATION

KEY_CACHED_INFORMATION

KEY_FULL_INFORMATION

KEY_INFORMATION_CLASS

KEY_NAME_INFORMATION

KEY_NODE_INFORMATION

KEY_VIRTUALIZATION_INFORMATION

Using Nt and Zw Versions of the Native System Services Routines

ZwClose

ZwEnumerateKey

ZwOpenKey

View the official Windows Driver Kit DDI reference

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NTinternals.net (undocumented.ntinternals.net)

This function is documented in Windows Driver Kit.

See ZwQueryKey in NT DDK or 2000 DDK for detailed description.

See also

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