#ifndef _NTREGAPI_H

/**
 * Returns fixed-size cached key statistics without appending a name or class.
 * Use the counts/maxima to plan value and direct-subkey enumeration, not as a
 * guarantee that later calls see the same state. Lengths and maxima are bytes.
 * \remarks The native/WoW64 query requires at least 40 bytes and
 * returns ResultLength = 40. A shorter buffer returns STATUS_BUFFER_TOO_SMALL,
 * not a partial cached record. NameLength at offset 32 describes the final key
 * component, but no name follows it; query basic/name information for the text.
 * Bytes 36 through 39 are trailing padding, not another field. Ordinary output
 * sets TitleIndex to 0. Do not infer semantics from padding contents.
 * \sa https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/ntddk/ns-ntddk-_key_cached_information
 */
typedef struct _KEY_CACHED_INFORMATION
{
    LARGE_INTEGER LastWriteTime;
    ULONG TitleIndex;
    ULONG SubKeys;
    ULONG MaxNameLength;
    ULONG Values;
    ULONG MaxValueNameLength;
    ULONG MaxValueDataLength;
    ULONG NameLength;
} KEY_CACHED_INFORMATION, *PKEY_CACHED_INFORMATION;

#endif
View code on GitHub

// ntddk.h

typedef struct _KEY_CACHED_INFORMATION {
  LARGE_INTEGER LastWriteTime;
  ULONG         TitleIndex;
  ULONG         SubKeys;
  ULONG         MaxNameLen;
  ULONG         Values;
  ULONG         MaxValueNameLen;
  ULONG         MaxValueDataLen;
  ULONG         NameLength;
} KEY_CACHED_INFORMATION, *PKEY_CACHED_INFORMATION;
View the official Windows Driver Kit DDI reference

NtDoc

This structure is documented in Windows Driver Kit.

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Windows Driver Kit DDI reference (ns-ntddk-_key_cached_information)

_KEY_CACHED_INFORMATION structure

Description

The KEY_CACHED_INFORMATION structure holds the cached information available for a registry key or subkey.

Members

`LastWriteTime`

The last time the key or any of its values changed. This time value is expressed in absolute system time format. Absolute system time is the number of 100-nanosecond intervals since the start of the year 1601 in the Gregorian calendar.

`TitleIndex`

Device and intermediate drivers should ignore this member.

`SubKeys`

The number of subkeys for a key.

`MaxNameLen`

The maximum number of bytes for a subkey name.

`Values`

The number of value entries.

`MaxValueNameLen`

The maximum length, in bytes, of any value entry name.

`MaxValueDataLen`

The maximum length, in bytes, of a value entry data field.

`NameLength`

The size, in bytes, of the key name.

KEY_CACHED_INFORMATION - NtDoc