#ifndef _NTRTL_H

NTSYSAPI
NTSTATUS
NTAPI
RtlCheckRegistryKey(
    _In_ ULONG RelativeTo,
    _In_ PCWSTR Path
    );

#endif
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// wdm.h

NTSYSAPI NTSTATUS RtlCheckRegistryKey(
  [in] ULONG RelativeTo,
  [in] PWSTR Path
);
View the official Windows Driver Kit DDI reference

NtDoc

Windows Driver Kit DDI reference (nf-wdm-rtlcheckregistrykey)

The RtlCheckRegistryKey routine checks for the existence of a given named key in the registry.

Specifies whether Path is an absolute registry path or is relative to a predefined key path as one of the following.

Value	Meaning
RTL_REGISTRY_ABSOLUTE	Path is an absolute registry path.
RTL_REGISTRY_CONTROL	Path is relative to \Registry\Machine\System\CurrentControlSet\Control.
RTL_REGISTRY_DEVICEMAP	Path is relative to \Registry\Machine\Hardware\DeviceMap.
RTL_REGISTRY_SERVICES	Path is relative to \Registry\Machine\System\CurrentControlSet\Services.
RTL_REGISTRY_USER	Path is relative to the registry settings for the current user. (For a system process, this is \Users.Default.) This is equivalent to HKEY_CURRENT_USER in user mode.
RTL_REGISTRY_WINDOWS_NT	Path is relative to \Registry\Machine\Software\Microsoft\Windows NT\CurrentVersion.
RTL_REGISTRY_HANDLE	This value should not be passed into this routine. Despite the redundancy of a check for the existence of an already-opened key, it has the side effect of closing the passed handle.

Specifies the registry path according to the RelativeTo value. If RTL_REGISTRY_HANDLE is set, Path is a handle to be used directly.

If the given named key exists in the registry along the given relative path, RtlCheckRegistryKey returns STATUS_SUCCESS.