#ifndef _NTEXAPI_H
#if (PHNT_MODE != PHNT_MODE_KERNEL)

/**
 * The NtOpenMutant routine opens a handle to an existing mutant object.
 *
 * @param MutantHandle A pointer to a variable that receives the mutant object handle.
 * @param DesiredAccess The access mask that specifies the requested access to the mutant object.
 * @param ObjectAttributes A pointer to an OBJECT_ATTRIBUTES structure that specifies the object attributes.
 * @return NTSTATUS Successful or errant status.
 */
NTSYSCALLAPI
NTSTATUS
NTAPI
NtOpenMutant(
    _Out_ PHANDLE MutantHandle,
    _In_ ACCESS_MASK DesiredAccess,
    _In_ PCOBJECT_ATTRIBUTES ObjectAttributes
    );

#endif
#endif
View code on GitHub

#ifndef _NTZWAPI_H

NTSYSCALLAPI
NTSTATUS
NTAPI
ZwOpenMutant(
    _Out_ PHANDLE MutantHandle,
    _In_ ACCESS_MASK DesiredAccess,
    _In_ PCOBJECT_ATTRIBUTES ObjectAttributes
    );

#endif
View code on GitHub