RtlUnicodeStringToOemString

// ntdll.dll
#include <windows.h>

NTSTATUS RtlUnicodeStringToOemString(
    STRING* DestinationString,
    UNICODE_STRING* SourceString,
    BOOLEAN AllocateDestinationString
);

<DllImport("ntdll.dll", ExactSpelling:=True)>
Public Shared Function RtlUnicodeStringToOemString(
    DestinationString As IntPtr,   ' STRING* in/out
    SourceString As IntPtr,   ' UNICODE_STRING* in/out
    <MarshalAs(UnmanagedType.U1)> AllocateDestinationString As Boolean   ' BOOLEAN
) As Integer
End Function

' DestinationString : STRING* in/out
' SourceString : UNICODE_STRING* in/out
' AllocateDestinationString : BOOLEAN
Declare PtrSafe Function RtlUnicodeStringToOemString Lib "ntdll" ( _
    ByVal DestinationString As LongPtr, _
    ByVal SourceString As LongPtr, _
    ByVal AllocateDestinationString As Byte) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

RtlUnicodeStringToOemString = ctypes.windll.ntdll.RtlUnicodeStringToOemString
RtlUnicodeStringToOemString.restype = ctypes.c_int
RtlUnicodeStringToOemString.argtypes = [
    ctypes.c_void_p,  # DestinationString : STRING* in/out
    ctypes.c_void_p,  # SourceString : UNICODE_STRING* in/out
    ctypes.c_byte,  # AllocateDestinationString : BOOLEAN
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('ntdll.dll')
RtlUnicodeStringToOemString = Fiddle::Function.new(
  lib['RtlUnicodeStringToOemString'],
  [
    Fiddle::TYPE_VOIDP,  # DestinationString : STRING* in/out
    Fiddle::TYPE_VOIDP,  # SourceString : UNICODE_STRING* in/out
    Fiddle::TYPE_CHAR,  # AllocateDestinationString : BOOLEAN
  ],
  Fiddle::TYPE_INT)

#[link(name = "ntdll")]
extern "system" {
    fn RtlUnicodeStringToOemString(
        DestinationString: *mut STRING,  // STRING* in/out
        SourceString: *mut UNICODE_STRING,  // UNICODE_STRING* in/out
        AllocateDestinationString: u8  // BOOLEAN
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("ntdll.dll")]
public static extern int RtlUnicodeStringToOemString(IntPtr DestinationString, IntPtr SourceString, [MarshalAs(UnmanagedType.U1)] bool AllocateDestinationString);
"@
$api = Add-Type -MemberDefinition $sig -Name 'ntdll_RtlUnicodeStringToOemString' -Namespace Win32 -PassThru
# $api::RtlUnicodeStringToOemString(DestinationString, SourceString, AllocateDestinationString)

#uselib "ntdll.dll"
#func global RtlUnicodeStringToOemString "RtlUnicodeStringToOemString" sptr, sptr, sptr
; RtlUnicodeStringToOemString varptr(DestinationString), varptr(SourceString), AllocateDestinationString   ; 戻り値は stat
; DestinationString : STRING* in/out -> "sptr"
; SourceString : UNICODE_STRING* in/out -> "sptr"
; AllocateDestinationString : BOOLEAN -> "sptr"
; ※HSP3.7は #func のため戻り値はシステム変数 stat に格納されます。

#uselib "ntdll.dll"
#cfunc global RtlUnicodeStringToOemString "RtlUnicodeStringToOemString" var, var, int
; res = RtlUnicodeStringToOemString(DestinationString, SourceString, AllocateDestinationString)
; DestinationString : STRING* in/out -> "var"
; SourceString : UNICODE_STRING* in/out -> "var"
; AllocateDestinationString : BOOLEAN -> "int"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

; NTSTATUS RtlUnicodeStringToOemString(STRING* DestinationString, UNICODE_STRING* SourceString, BOOLEAN AllocateDestinationString)
#uselib "ntdll.dll"
#cfunc global RtlUnicodeStringToOemString "RtlUnicodeStringToOemString" var, var, int
; res = RtlUnicodeStringToOemString(DestinationString, SourceString, AllocateDestinationString)
; DestinationString : STRING* in/out -> "var"
; SourceString : UNICODE_STRING* in/out -> "var"
; AllocateDestinationString : BOOLEAN -> "int"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

import (
	"golang.org/x/sys/windows"
	"unsafe"
)

var (
	ntdll = windows.NewLazySystemDLL("ntdll.dll")
	procRtlUnicodeStringToOemString = ntdll.NewProc("RtlUnicodeStringToOemString")
)

// DestinationString (STRING* in/out), SourceString (UNICODE_STRING* in/out), AllocateDestinationString (BOOLEAN)
r1, _, err := procRtlUnicodeStringToOemString.Call(
	uintptr(DestinationString),
	uintptr(SourceString),
	uintptr(AllocateDestinationString),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // NTSTATUS

function RtlUnicodeStringToOemString(
  DestinationString: Pointer;   // STRING* in/out
  SourceString: Pointer;   // UNICODE_STRING* in/out
  AllocateDestinationString: ByteBool   // BOOLEAN
): Integer; stdcall;
  external 'ntdll.dll' name 'RtlUnicodeStringToOemString';

result := DllCall("ntdll\RtlUnicodeStringToOemString"
    , "Ptr", DestinationString   ; STRING* in/out
    , "Ptr", SourceString   ; UNICODE_STRING* in/out
    , "Char", AllocateDestinationString   ; BOOLEAN
    , "Int")   ; return: NTSTATUS

●RtlUnicodeStringToOemString(DestinationString, SourceString, AllocateDestinationString) = DLL("ntdll.dll", "int RtlUnicodeStringToOemString(void*, void*, byte)")
# 呼び出し: RtlUnicodeStringToOemString(DestinationString, SourceString, AllocateDestinationString)
# DestinationString : STRING* in/out -> "void*"
# SourceString : UNICODE_STRING* in/out -> "void*"
# AllocateDestinationString : BOOLEAN -> "byte"
# なでしこ1は32bit・ANSI(Shift_JIS)。文字列=char*(ANSI)、ポインタ/ハンドル=void*(4byte)。