NtQuerySystemEnvironmentValueEx - NtDoc

#ifndef _NTEXAPI_H
#if (PHNT_MODE != PHNT_MODE_KERNEL)

NTSYSCALLAPI
NTSTATUS
NTAPI
NtQuerySystemEnvironmentValueEx(
    _In_ PUNICODE_STRING VariableName,
    _In_ PCGUID VendorGuid,
    _Out_writes_bytes_opt_(*ValueLength) PVOID Value,
    _Inout_ PULONG ValueLength,
    _Out_opt_ PULONG Attributes // EFI_VARIABLE_*
    );

#endif
#endif
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#ifndef _NTZWAPI_H

NTSYSCALLAPI
NTSTATUS
NTAPI
ZwQuerySystemEnvironmentValueEx(
    _In_ PUNICODE_STRING VariableName,
    _In_ PCGUID VendorGuid,
    _Out_writes_bytes_opt_(*ValueLength) PVOID Value,
    _Inout_ PULONG ValueLength,
    _Out_opt_ PULONG Attributes // EFI_VARIABLE_*
    );

#endif
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