RtlNtStatusToDosError - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers

#ifndef _NTRTL_H

// Errors

_When_(Status < 0, _Out_range_(>, 0))
_When_(Status >= 0, _Out_range_(==, 0))
NTSYSAPI
ULONG
NTAPI
RtlNtStatusToDosError(
    _In_ NTSTATUS Status
    );

#endif
View code on GitHub

This function is documented in Windows Driver Kit.

Edit description on GitHub