MsiDoActionW

// msi.dll  (Unicode / -W)
#include <windows.h>

DWORD MsiDoActionW(
    MSIHANDLE hInstall,
    LPCWSTR szAction
);

<DllImport("msi.dll", CharSet:=CharSet.Unicode, ExactSpelling:=True)>
Public Shared Function MsiDoActionW(
    hInstall As UInteger,   ' MSIHANDLE
    <MarshalAs(UnmanagedType.LPWStr)> szAction As String   ' LPCWSTR
) As UInteger
End Function

' hInstall : MSIHANDLE
' szAction : LPCWSTR
Declare PtrSafe Function MsiDoActionW Lib "msi" ( _
    ByVal hInstall As Long, _
    ByVal szAction As LongPtr) As Long
' Unicode(W): 文字列は ByVal As LongPtr とし StrPtr(unicodeStr) を渡す
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

MsiDoActionW = ctypes.windll.msi.MsiDoActionW
MsiDoActionW.restype = wintypes.DWORD
MsiDoActionW.argtypes = [
    wintypes.DWORD,  # hInstall : MSIHANDLE
    wintypes.LPCWSTR,  # szAction : LPCWSTR
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('msi.dll')
MsiDoActionW = Fiddle::Function.new(
  lib['MsiDoActionW'],
  [
    -Fiddle::TYPE_INT,  # hInstall : MSIHANDLE
    Fiddle::TYPE_VOIDP,  # szAction : LPCWSTR
  ],
  -Fiddle::TYPE_INT)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

#[link(name = "msi")]
extern "system" {
    fn MsiDoActionW(
        hInstall: u32,  // MSIHANDLE
        szAction: *const u16  // LPCWSTR
    ) -> u32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("msi.dll", CharSet = CharSet.Unicode)]
public static extern uint MsiDoActionW(uint hInstall, [MarshalAs(UnmanagedType.LPWStr)] string szAction);
"@
$api = Add-Type -MemberDefinition $sig -Name 'msi_MsiDoActionW' -Namespace Win32 -PassThru
# $api::MsiDoActionW(hInstall, szAction)

#uselib "msi.dll"
#func global MsiDoActionW "MsiDoActionW" wptr, wptr
; MsiDoActionW hInstall, szAction   ; 戻り値は stat
; hInstall : MSIHANDLE -> "wptr"
; szAction : LPCWSTR -> "wptr"
; ※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 "msi.dll"
#cfunc global MsiDoActionW "MsiDoActionW" int, wstr
; res = MsiDoActionW(hInstall, szAction)
; hInstall : MSIHANDLE -> "int"
; szAction : LPCWSTR -> "wstr"

; DWORD MsiDoActionW(MSIHANDLE hInstall, LPCWSTR szAction)
#uselib "msi.dll"
#cfunc global MsiDoActionW "MsiDoActionW" int, wstr
; res = MsiDoActionW(hInstall, szAction)
; hInstall : MSIHANDLE -> "int"
; szAction : LPCWSTR -> "wstr"

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

var (
	msi = windows.NewLazySystemDLL("msi.dll")
	procMsiDoActionW = msi.NewProc("MsiDoActionW")
)

// hInstall (MSIHANDLE), szAction (LPCWSTR)
r1, _, err := procMsiDoActionW.Call(
	uintptr(hInstall),
	uintptr(unsafe.Pointer(windows.StringToUTF16Ptr(szAction))),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // DWORD

function MsiDoActionW(
  hInstall: DWORD;   // MSIHANDLE
  szAction: PWideChar   // LPCWSTR
): DWORD; stdcall;
  external 'msi.dll' name 'MsiDoActionW';

result := DllCall("msi\MsiDoActionW"
    , "UInt", hInstall   ; MSIHANDLE
    , "WStr", szAction   ; LPCWSTR
    , "UInt")   ; return: DWORD

●MsiDoActionW(hInstall, szAction) = DLL("msi.dll", "dword MsiDoActionW(dword, char*)")
# 呼び出し: MsiDoActionW(hInstall, szAction)
# hInstall : MSIHANDLE -> "dword"
# szAction : LPCWSTR -> "char*"
# 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)。
# ※-W(Unicode)関数。なでしこ1はANSIのため -A 版の利用を推奨。