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 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.

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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