#ifndef _NTEXAPI_H
#if (PHNT_MODE != PHNT_MODE_KERNEL)

/**
 * The NtShutdownSystem routine initiates a system shutdown using the specified
 * shutdown action.
 *
 * \param Action A SHUTDOWN_ACTION value that specifies whether the system
 * should halt, reboot, power off, or reboot for recovery.
 * \return NTSTATUS Successful or errant status.
 * \remarks The calling process must have the SE_SHUTDOWN_NAME privilege.
 */
_Kernel_entry_
NTSYSCALLAPI
NTSTATUS
NTAPI
NtShutdownSystem(
    _In_ SHUTDOWN_ACTION Action
    );

#endif
#endif
View code on GitHub

#ifndef _NTZWAPI_H

_Kernel_entry_
NTSYSCALLAPI
NTSTATUS
NTAPI
ZwShutdownSystem(
    _In_ SHUTDOWN_ACTION Action
    );

#endif
View code on GitHub