DecryptFileA

// ADVAPI32.dll  (ANSI / -A)
#include <windows.h>

BOOL DecryptFileA(
    LPCSTR lpFileName,
    DWORD dwReserved   // optional
);

<DllImport("ADVAPI32.dll", CharSet:=CharSet.Ansi, SetLastError:=True, ExactSpelling:=True)>
Public Shared Function DecryptFileA(
    <MarshalAs(UnmanagedType.LPStr)> lpFileName As String,   ' LPCSTR
    dwReserved As UInteger   ' DWORD optional
) As Boolean
End Function

' lpFileName : LPCSTR
' dwReserved : DWORD optional
Declare PtrSafe Function DecryptFileA Lib "advapi32" ( _
    ByVal lpFileName As String, _
    ByVal dwReserved As Long) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

DecryptFileA = ctypes.windll.advapi32.DecryptFileA
DecryptFileA.restype = wintypes.BOOL
DecryptFileA.argtypes = [
    wintypes.LPCSTR,  # lpFileName : LPCSTR
    wintypes.DWORD,  # dwReserved : DWORD optional
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('ADVAPI32.dll')
DecryptFileA = Fiddle::Function.new(
  lib['DecryptFileA'],
  [
    Fiddle::TYPE_VOIDP,  # lpFileName : LPCSTR
    -Fiddle::TYPE_INT,  # dwReserved : DWORD optional
  ],
  Fiddle::TYPE_INT)

#[link(name = "advapi32")]
extern "system" {
    fn DecryptFileA(
        lpFileName: *const u8,  // LPCSTR
        dwReserved: u32  // DWORD optional
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("ADVAPI32.dll", CharSet = CharSet.Ansi, SetLastError = true)]
public static extern bool DecryptFileA([MarshalAs(UnmanagedType.LPStr)] string lpFileName, uint dwReserved);
"@
$api = Add-Type -MemberDefinition $sig -Name 'ADVAPI32_DecryptFileA' -Namespace Win32 -PassThru
# $api::DecryptFileA(lpFileName, dwReserved)

#uselib "ADVAPI32.dll"
#func global DecryptFileA "DecryptFileA" sptr, sptr
; DecryptFileA lpFileName, dwReserved   ; 戻り値は stat
; lpFileName : LPCSTR -> "sptr"
; dwReserved : DWORD optional -> "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 "ADVAPI32.dll"
#cfunc global DecryptFileA "DecryptFileA" str, int
; res = DecryptFileA(lpFileName, dwReserved)
; lpFileName : LPCSTR -> "str"
; dwReserved : DWORD optional -> "int"

; BOOL DecryptFileA(LPCSTR lpFileName, DWORD dwReserved)
#uselib "ADVAPI32.dll"
#cfunc global DecryptFileA "DecryptFileA" str, int
; res = DecryptFileA(lpFileName, dwReserved)
; lpFileName : LPCSTR -> "str"
; dwReserved : DWORD optional -> "int"

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

var (
	advapi32 = windows.NewLazySystemDLL("ADVAPI32.dll")
	procDecryptFileA = advapi32.NewProc("DecryptFileA")
)

// lpFileName (LPCSTR), dwReserved (DWORD optional)
r1, _, err := procDecryptFileA.Call(
	uintptr(unsafe.Pointer(windows.BytePtrFromString(lpFileName))),
	uintptr(dwReserved),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // BOOL

function DecryptFileA(
  lpFileName: PAnsiChar;   // LPCSTR
  dwReserved: DWORD   // DWORD optional
): BOOL; stdcall;
  external 'ADVAPI32.dll' name 'DecryptFileA';

result := DllCall("ADVAPI32\DecryptFileA"
    , "AStr", lpFileName   ; LPCSTR
    , "UInt", dwReserved   ; DWORD optional
    , "Int")   ; return: BOOL

●DecryptFileA(lpFileName, dwReserved) = DLL("ADVAPI32.dll", "bool DecryptFileA(char*, dword)")
# 呼び出し: DecryptFileA(lpFileName, dwReserved)
# lpFileName : LPCSTR -> "char*"
# dwReserved : DWORD optional -> "dword"
# 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)。