SHSetFolderPathW

// SHELL32.dll  (Unicode / -W)
#include <windows.h>

HRESULT SHSetFolderPathW(
    INT csidl,
    HANDLE hToken,   // optional
    DWORD dwFlags,
    LPCWSTR pszPath
);

<DllImport("SHELL32.dll", CharSet:=CharSet.Unicode, ExactSpelling:=True)>
Public Shared Function SHSetFolderPathW(
    csidl As Integer,   ' INT
    hToken As IntPtr,   ' HANDLE optional
    dwFlags As UInteger,   ' DWORD
    <MarshalAs(UnmanagedType.LPWStr)> pszPath As String   ' LPCWSTR
) As Integer
End Function

' csidl : INT
' hToken : HANDLE optional
' dwFlags : DWORD
' pszPath : LPCWSTR
Declare PtrSafe Function SHSetFolderPathW Lib "shell32" ( _
    ByVal csidl As Long, _
    ByVal hToken As LongPtr, _
    ByVal dwFlags As Long, _
    ByVal pszPath 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

SHSetFolderPathW = ctypes.windll.shell32.SHSetFolderPathW
SHSetFolderPathW.restype = ctypes.c_int
SHSetFolderPathW.argtypes = [
    ctypes.c_int,  # csidl : INT
    wintypes.HANDLE,  # hToken : HANDLE optional
    wintypes.DWORD,  # dwFlags : DWORD
    wintypes.LPCWSTR,  # pszPath : LPCWSTR
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('SHELL32.dll')
SHSetFolderPathW = Fiddle::Function.new(
  lib['SHSetFolderPathW'],
  [
    Fiddle::TYPE_INT,  # csidl : INT
    Fiddle::TYPE_VOIDP,  # hToken : HANDLE optional
    -Fiddle::TYPE_INT,  # dwFlags : DWORD
    Fiddle::TYPE_VOIDP,  # pszPath : LPCWSTR
  ],
  Fiddle::TYPE_INT)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

#[link(name = "shell32")]
extern "system" {
    fn SHSetFolderPathW(
        csidl: i32,  // INT
        hToken: *mut core::ffi::c_void,  // HANDLE optional
        dwFlags: u32,  // DWORD
        pszPath: *const u16  // LPCWSTR
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("SHELL32.dll", CharSet = CharSet.Unicode)]
public static extern int SHSetFolderPathW(int csidl, IntPtr hToken, uint dwFlags, [MarshalAs(UnmanagedType.LPWStr)] string pszPath);
"@
$api = Add-Type -MemberDefinition $sig -Name 'SHELL32_SHSetFolderPathW' -Namespace Win32 -PassThru
# $api::SHSetFolderPathW(csidl, hToken, dwFlags, pszPath)

#uselib "SHELL32.dll"
#func global SHSetFolderPathW "SHSetFolderPathW" wptr, wptr, wptr, wptr
; SHSetFolderPathW csidl, hToken, dwFlags, pszPath   ; 戻り値は stat
; csidl : INT -> "wptr"
; hToken : HANDLE optional -> "wptr"
; dwFlags : DWORD -> "wptr"
; pszPath : 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 "SHELL32.dll"
#cfunc global SHSetFolderPathW "SHSetFolderPathW" int, sptr, int, wstr
; res = SHSetFolderPathW(csidl, hToken, dwFlags, pszPath)
; csidl : INT -> "int"
; hToken : HANDLE optional -> "sptr"
; dwFlags : DWORD -> "int"
; pszPath : LPCWSTR -> "wstr"

; HRESULT SHSetFolderPathW(INT csidl, HANDLE hToken, DWORD dwFlags, LPCWSTR pszPath)
#uselib "SHELL32.dll"
#cfunc global SHSetFolderPathW "SHSetFolderPathW" int, intptr, int, wstr
; res = SHSetFolderPathW(csidl, hToken, dwFlags, pszPath)
; csidl : INT -> "int"
; hToken : HANDLE optional -> "intptr"
; dwFlags : DWORD -> "int"
; pszPath : LPCWSTR -> "wstr"

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

var (
	shell32 = windows.NewLazySystemDLL("SHELL32.dll")
	procSHSetFolderPathW = shell32.NewProc("SHSetFolderPathW")
)

// csidl (INT), hToken (HANDLE optional), dwFlags (DWORD), pszPath (LPCWSTR)
r1, _, err := procSHSetFolderPathW.Call(
	uintptr(csidl),
	uintptr(hToken),
	uintptr(dwFlags),
	uintptr(unsafe.Pointer(windows.StringToUTF16Ptr(pszPath))),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // HRESULT

function SHSetFolderPathW(
  csidl: Integer;   // INT
  hToken: THandle;   // HANDLE optional
  dwFlags: DWORD;   // DWORD
  pszPath: PWideChar   // LPCWSTR
): Integer; stdcall;
  external 'SHELL32.dll' name 'SHSetFolderPathW';

result := DllCall("SHELL32\SHSetFolderPathW"
    , "Int", csidl   ; INT
    , "Ptr", hToken   ; HANDLE optional
    , "UInt", dwFlags   ; DWORD
    , "WStr", pszPath   ; LPCWSTR
    , "Int")   ; return: HRESULT

●SHSetFolderPathW(csidl, hToken, dwFlags, pszPath) = DLL("SHELL32.dll", "int SHSetFolderPathW(int, void*, dword, char*)")
# 呼び出し: SHSetFolderPathW(csidl, hToken, dwFlags, pszPath)
# csidl : INT -> "int"
# hToken : HANDLE optional -> "void*"
# dwFlags : DWORD -> "dword"
# pszPath : 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。