SHGetKnownFolderPath

// SHELL32.dll
#include <windows.h>

HRESULT SHGetKnownFolderPath(
    const GUID* rfid,
    DWORD dwFlags,
    HANDLE hToken,   // optional
    LPWSTR* ppszPath
);

<DllImport("SHELL32.dll", ExactSpelling:=True)>
Public Shared Function SHGetKnownFolderPath(
    ByRef rfid As Guid,   ' GUID*
    dwFlags As UInteger,   ' DWORD
    hToken As IntPtr,   ' HANDLE optional
    ppszPath As IntPtr   ' LPWSTR* out
) As Integer
End Function

' rfid : GUID*
' dwFlags : DWORD
' hToken : HANDLE optional
' ppszPath : LPWSTR* out
Declare PtrSafe Function SHGetKnownFolderPath Lib "shell32" ( _
    ByVal rfid As LongPtr, _
    ByVal dwFlags As Long, _
    ByVal hToken As LongPtr, _
    ByVal ppszPath As LongPtr) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

SHGetKnownFolderPath = ctypes.windll.shell32.SHGetKnownFolderPath
SHGetKnownFolderPath.restype = ctypes.c_int
SHGetKnownFolderPath.argtypes = [
    ctypes.c_void_p,  # rfid : GUID*
    wintypes.DWORD,  # dwFlags : DWORD
    wintypes.HANDLE,  # hToken : HANDLE optional
    ctypes.c_void_p,  # ppszPath : LPWSTR* out
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('SHELL32.dll')
SHGetKnownFolderPath = Fiddle::Function.new(
  lib['SHGetKnownFolderPath'],
  [
    Fiddle::TYPE_VOIDP,  # rfid : GUID*
    -Fiddle::TYPE_INT,  # dwFlags : DWORD
    Fiddle::TYPE_VOIDP,  # hToken : HANDLE optional
    Fiddle::TYPE_VOIDP,  # ppszPath : LPWSTR* out
  ],
  Fiddle::TYPE_INT)

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

$sig = @"
[DllImport("SHELL32.dll")]
public static extern int SHGetKnownFolderPath(ref Guid rfid, uint dwFlags, IntPtr hToken, IntPtr ppszPath);
"@
$api = Add-Type -MemberDefinition $sig -Name 'SHELL32_SHGetKnownFolderPath' -Namespace Win32 -PassThru
# $api::SHGetKnownFolderPath(rfid, dwFlags, hToken, ppszPath)

#uselib "SHELL32.dll"
#func global SHGetKnownFolderPath "SHGetKnownFolderPath" sptr, sptr, sptr, sptr
; SHGetKnownFolderPath varptr(rfid), dwFlags, hToken, varptr(ppszPath)   ; 戻り値は stat
; rfid : GUID* -> "sptr"
; dwFlags : DWORD -> "sptr"
; hToken : HANDLE optional -> "sptr"
; ppszPath : LPWSTR* out -> "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 "SHELL32.dll"
#cfunc global SHGetKnownFolderPath "SHGetKnownFolderPath" var, int, sptr, var
; res = SHGetKnownFolderPath(rfid, dwFlags, hToken, ppszPath)
; rfid : GUID* -> "var"
; dwFlags : DWORD -> "int"
; hToken : HANDLE optional -> "sptr"
; ppszPath : LPWSTR* 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。

; HRESULT SHGetKnownFolderPath(GUID* rfid, DWORD dwFlags, HANDLE hToken, LPWSTR* ppszPath)
#uselib "SHELL32.dll"
#cfunc global SHGetKnownFolderPath "SHGetKnownFolderPath" var, int, intptr, var
; res = SHGetKnownFolderPath(rfid, dwFlags, hToken, ppszPath)
; rfid : GUID* -> "var"
; dwFlags : DWORD -> "int"
; hToken : HANDLE optional -> "intptr"
; ppszPath : LPWSTR* 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 (
	shell32 = windows.NewLazySystemDLL("SHELL32.dll")
	procSHGetKnownFolderPath = shell32.NewProc("SHGetKnownFolderPath")
)

// rfid (GUID*), dwFlags (DWORD), hToken (HANDLE optional), ppszPath (LPWSTR* out)
r1, _, err := procSHGetKnownFolderPath.Call(
	uintptr(rfid),
	uintptr(dwFlags),
	uintptr(hToken),
	uintptr(ppszPath),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // HRESULT

function SHGetKnownFolderPath(
  rfid: PGUID;   // GUID*
  dwFlags: DWORD;   // DWORD
  hToken: THandle;   // HANDLE optional
  ppszPath: PPWideChar   // LPWSTR* out
): Integer; stdcall;
  external 'SHELL32.dll' name 'SHGetKnownFolderPath';

result := DllCall("SHELL32\SHGetKnownFolderPath"
    , "Ptr", rfid   ; GUID*
    , "UInt", dwFlags   ; DWORD
    , "Ptr", hToken   ; HANDLE optional
    , "Ptr", ppszPath   ; LPWSTR* out
    , "Int")   ; return: HRESULT

●SHGetKnownFolderPath(rfid, dwFlags, hToken, ppszPath) = DLL("SHELL32.dll", "int SHGetKnownFolderPath(void*, dword, void*, void*)")
# 呼び出し: SHGetKnownFolderPath(rfid, dwFlags, hToken, ppszPath)
# rfid : GUID* -> "void*"
# dwFlags : DWORD -> "dword"
# hToken : HANDLE optional -> "void*"
# ppszPath : LPWSTR* out -> "void*"
# 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)。