NtQueryOpenSubKeys - NtDoc

#ifndef _NTREGAPI_H

/**
 * Queries the number of open subkeys of a registry key.
 * 
 * @param TargetKey Pointer to the object attributes of the target key.
 * @param HandleCount Pointer to a variable to receive the handle count.
 * @return NTSTATUS Successful or errant status.
 */
NTSYSCALLAPI
NTSTATUS
NTAPI
NtQueryOpenSubKeys(
    _In_ POBJECT_ATTRIBUTES TargetKey,
    _Out_ PULONG HandleCount
    );

#endif
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#ifndef _NTZWAPI_H

NTSYSCALLAPI
NTSTATUS
NTAPI
ZwQueryOpenSubKeys(
    _In_ POBJECT_ATTRIBUTES TargetKey,
    _Out_ PULONG HandleCount
    );

#endif
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