#ifndef _NTEXAPI_H
#if (PHNT_MODE != PHNT_MODE_KERNEL)

/**
 * The NtSetSystemInformation routine sets information about the system.
 *
 * \param SystemInformationClass The type of information to be set.
 * \param SystemInformation A pointer to a buffer that receives the requested information.
 * \param SystemInformationLength The size of the buffer pointed to by SystemInformation.
 * \return NTSTATUS Successful or errant status.
 */
NTSYSCALLAPI
NTSTATUS
NTAPI
NtSetSystemInformation(
    _In_ SYSTEM_INFORMATION_CLASS SystemInformationClass,
    _In_reads_bytes_opt_(SystemInformationLength) PVOID SystemInformation,
    _In_ ULONG SystemInformationLength
    );

#endif
#endif
View code on GitHub

#ifndef _NTZWAPI_H

NTSYSCALLAPI
NTSTATUS
NTAPI
ZwSetSystemInformation(
    _In_ SYSTEM_INFORMATION_CLASS SystemInformationClass,
    _In_reads_bytes_opt_(SystemInformationLength) PVOID SystemInformation,
    _In_ ULONG SystemInformationLength
    );

#endif
View code on GitHub