MsiEnumFeaturesW

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

DWORD MsiEnumFeaturesW(
    LPCWSTR szProduct,
    DWORD iFeatureIndex,
    LPWSTR lpFeatureBuf,
    LPWSTR lpParentBuf   // optional
);

<DllImport("msi.dll", CharSet:=CharSet.Unicode, ExactSpelling:=True)>
Public Shared Function MsiEnumFeaturesW(
    <MarshalAs(UnmanagedType.LPWStr)> szProduct As String,   ' LPCWSTR
    iFeatureIndex As UInteger,   ' DWORD
    <MarshalAs(UnmanagedType.LPWStr)> lpFeatureBuf As System.Text.StringBuilder,   ' LPWSTR out
    <MarshalAs(UnmanagedType.LPWStr)> lpParentBuf As System.Text.StringBuilder   ' LPWSTR optional, out
) As UInteger
End Function

' szProduct : LPCWSTR
' iFeatureIndex : DWORD
' lpFeatureBuf : LPWSTR out
' lpParentBuf : LPWSTR optional, out
Declare PtrSafe Function MsiEnumFeaturesW Lib "msi" ( _
    ByVal szProduct As LongPtr, _
    ByVal iFeatureIndex As Long, _
    ByVal lpFeatureBuf As LongPtr, _
    ByVal lpParentBuf 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

MsiEnumFeaturesW = ctypes.windll.msi.MsiEnumFeaturesW
MsiEnumFeaturesW.restype = wintypes.DWORD
MsiEnumFeaturesW.argtypes = [
    wintypes.LPCWSTR,  # szProduct : LPCWSTR
    wintypes.DWORD,  # iFeatureIndex : DWORD
    wintypes.LPWSTR,  # lpFeatureBuf : LPWSTR out
    wintypes.LPWSTR,  # lpParentBuf : LPWSTR optional, out
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('msi.dll')
MsiEnumFeaturesW = Fiddle::Function.new(
  lib['MsiEnumFeaturesW'],
  [
    Fiddle::TYPE_VOIDP,  # szProduct : LPCWSTR
    -Fiddle::TYPE_INT,  # iFeatureIndex : DWORD
    Fiddle::TYPE_VOIDP,  # lpFeatureBuf : LPWSTR out
    Fiddle::TYPE_VOIDP,  # lpParentBuf : LPWSTR optional, out
  ],
  -Fiddle::TYPE_INT)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

#[link(name = "msi")]
extern "system" {
    fn MsiEnumFeaturesW(
        szProduct: *const u16,  // LPCWSTR
        iFeatureIndex: u32,  // DWORD
        lpFeatureBuf: *mut u16,  // LPWSTR out
        lpParentBuf: *mut u16  // LPWSTR optional, out
    ) -> u32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("msi.dll", CharSet = CharSet.Unicode)]
public static extern uint MsiEnumFeaturesW([MarshalAs(UnmanagedType.LPWStr)] string szProduct, uint iFeatureIndex, [MarshalAs(UnmanagedType.LPWStr)] System.Text.StringBuilder lpFeatureBuf, [MarshalAs(UnmanagedType.LPWStr)] System.Text.StringBuilder lpParentBuf);
"@
$api = Add-Type -MemberDefinition $sig -Name 'msi_MsiEnumFeaturesW' -Namespace Win32 -PassThru
# $api::MsiEnumFeaturesW(szProduct, iFeatureIndex, lpFeatureBuf, lpParentBuf)

#uselib "msi.dll"
#func global MsiEnumFeaturesW "MsiEnumFeaturesW" wptr, wptr, wptr, wptr
; MsiEnumFeaturesW szProduct, iFeatureIndex, varptr(lpFeatureBuf), varptr(lpParentBuf)   ; 戻り値は stat
; szProduct : LPCWSTR -> "wptr"
; iFeatureIndex : DWORD -> "wptr"
; lpFeatureBuf : LPWSTR out -> "wptr"
; lpParentBuf : LPWSTR optional, out -> "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 MsiEnumFeaturesW "MsiEnumFeaturesW" wstr, int, var, var
; res = MsiEnumFeaturesW(szProduct, iFeatureIndex, lpFeatureBuf, lpParentBuf)
; szProduct : LPCWSTR -> "wstr"
; iFeatureIndex : DWORD -> "int"
; lpFeatureBuf : LPWSTR out -> "var"
; lpParentBuf : LPWSTR optional, out -> "var"
; ※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。

; DWORD MsiEnumFeaturesW(LPCWSTR szProduct, DWORD iFeatureIndex, LPWSTR lpFeatureBuf, LPWSTR lpParentBuf)
#uselib "msi.dll"
#cfunc global MsiEnumFeaturesW "MsiEnumFeaturesW" wstr, int, var, var
; res = MsiEnumFeaturesW(szProduct, iFeatureIndex, lpFeatureBuf, lpParentBuf)
; szProduct : LPCWSTR -> "wstr"
; iFeatureIndex : DWORD -> "int"
; lpFeatureBuf : LPWSTR out -> "var"
; lpParentBuf : LPWSTR optional, out -> "var"
; ※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 (
	msi = windows.NewLazySystemDLL("msi.dll")
	procMsiEnumFeaturesW = msi.NewProc("MsiEnumFeaturesW")
)

// szProduct (LPCWSTR), iFeatureIndex (DWORD), lpFeatureBuf (LPWSTR out), lpParentBuf (LPWSTR optional, out)
r1, _, err := procMsiEnumFeaturesW.Call(
	uintptr(unsafe.Pointer(windows.StringToUTF16Ptr(szProduct))),
	uintptr(iFeatureIndex),
	uintptr(lpFeatureBuf),
	uintptr(lpParentBuf),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // DWORD

function MsiEnumFeaturesW(
  szProduct: PWideChar;   // LPCWSTR
  iFeatureIndex: DWORD;   // DWORD
  lpFeatureBuf: PWideChar;   // LPWSTR out
  lpParentBuf: PWideChar   // LPWSTR optional, out
): DWORD; stdcall;
  external 'msi.dll' name 'MsiEnumFeaturesW';

result := DllCall("msi\MsiEnumFeaturesW"
    , "WStr", szProduct   ; LPCWSTR
    , "UInt", iFeatureIndex   ; DWORD
    , "Ptr", lpFeatureBuf   ; LPWSTR out
    , "Ptr", lpParentBuf   ; LPWSTR optional, out
    , "UInt")   ; return: DWORD

●MsiEnumFeaturesW(szProduct, iFeatureIndex, lpFeatureBuf, lpParentBuf) = DLL("msi.dll", "dword MsiEnumFeaturesW(char*, dword, char*, char*)")
# 呼び出し: MsiEnumFeaturesW(szProduct, iFeatureIndex, lpFeatureBuf, lpParentBuf)
# szProduct : LPCWSTR -> "char*"
# iFeatureIndex : DWORD -> "dword"
# lpFeatureBuf : LPWSTR out -> "char*"
# lpParentBuf : LPWSTR optional, out -> "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。