#ifndef _NTRTL_H

NTSYSAPI
VOID
NTAPI
RtlCopyLuid(
    _Out_ PLUID DestinationLuid,
    _In_ PLUID SourceLuid
    );

#endif
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// ntifs.h

NTSYSAPI VOID RtlCopyLuid(
  [out] PLUID DestinationLuid,
  [in]  PLUID SourceLuid
);
View the official Windows Driver Kit DDI reference

NtDoc

Windows Driver Kit DDI reference (nf-ntifs-rtlcopyluid)

The RtlCopyLuid routine copies a locally unique identifier (LUID) to a buffer.

Pointer to a caller-allocated buffer to receive a copy of the source LUID structure. The buffer must be at least sizeof(LUID).

Pointer to the source LUID structure to be copied.

None

RtlCopyLuid does not check whether the LUID at SourceLuid is structurally valid.

For more information about security and access control, see Windows security model for driver developers and the documentation on these topics in the Windows SDK.