SHGetDiskFreeSpaceExW

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

BOOL SHGetDiskFreeSpaceExW(
    LPCWSTR pszDirectoryName,
    ULONGLONG* pulFreeBytesAvailableToCaller,   // optional
    ULONGLONG* pulTotalNumberOfBytes,   // optional
    ULONGLONG* pulTotalNumberOfFreeBytes   // optional
);

<DllImport("SHELL32.dll", CharSet:=CharSet.Unicode, ExactSpelling:=True)>
Public Shared Function SHGetDiskFreeSpaceExW(
    <MarshalAs(UnmanagedType.LPWStr)> pszDirectoryName As String,   ' LPCWSTR
    pulFreeBytesAvailableToCaller As IntPtr,   ' ULONGLONG* optional, out
    pulTotalNumberOfBytes As IntPtr,   ' ULONGLONG* optional, out
    pulTotalNumberOfFreeBytes As IntPtr   ' ULONGLONG* optional, out
) As Boolean
End Function

' pszDirectoryName : LPCWSTR
' pulFreeBytesAvailableToCaller : ULONGLONG* optional, out
' pulTotalNumberOfBytes : ULONGLONG* optional, out
' pulTotalNumberOfFreeBytes : ULONGLONG* optional, out
Declare PtrSafe Function SHGetDiskFreeSpaceExW Lib "shell32" ( _
    ByVal pszDirectoryName As LongPtr, _
    ByVal pulFreeBytesAvailableToCaller As LongPtr, _
    ByVal pulTotalNumberOfBytes As LongPtr, _
    ByVal pulTotalNumberOfFreeBytes 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

SHGetDiskFreeSpaceExW = ctypes.windll.shell32.SHGetDiskFreeSpaceExW
SHGetDiskFreeSpaceExW.restype = wintypes.BOOL
SHGetDiskFreeSpaceExW.argtypes = [
    wintypes.LPCWSTR,  # pszDirectoryName : LPCWSTR
    ctypes.POINTER(ctypes.c_ulonglong),  # pulFreeBytesAvailableToCaller : ULONGLONG* optional, out
    ctypes.POINTER(ctypes.c_ulonglong),  # pulTotalNumberOfBytes : ULONGLONG* optional, out
    ctypes.POINTER(ctypes.c_ulonglong),  # pulTotalNumberOfFreeBytes : ULONGLONG* optional, out
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('SHELL32.dll')
SHGetDiskFreeSpaceExW = Fiddle::Function.new(
  lib['SHGetDiskFreeSpaceExW'],
  [
    Fiddle::TYPE_VOIDP,  # pszDirectoryName : LPCWSTR
    Fiddle::TYPE_VOIDP,  # pulFreeBytesAvailableToCaller : ULONGLONG* optional, out
    Fiddle::TYPE_VOIDP,  # pulTotalNumberOfBytes : ULONGLONG* optional, out
    Fiddle::TYPE_VOIDP,  # pulTotalNumberOfFreeBytes : ULONGLONG* optional, out
  ],
  Fiddle::TYPE_INT)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

#[link(name = "shell32")]
extern "system" {
    fn SHGetDiskFreeSpaceExW(
        pszDirectoryName: *const u16,  // LPCWSTR
        pulFreeBytesAvailableToCaller: *mut u64,  // ULONGLONG* optional, out
        pulTotalNumberOfBytes: *mut u64,  // ULONGLONG* optional, out
        pulTotalNumberOfFreeBytes: *mut u64  // ULONGLONG* optional, out
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("SHELL32.dll", CharSet = CharSet.Unicode)]
public static extern bool SHGetDiskFreeSpaceExW([MarshalAs(UnmanagedType.LPWStr)] string pszDirectoryName, IntPtr pulFreeBytesAvailableToCaller, IntPtr pulTotalNumberOfBytes, IntPtr pulTotalNumberOfFreeBytes);
"@
$api = Add-Type -MemberDefinition $sig -Name 'SHELL32_SHGetDiskFreeSpaceExW' -Namespace Win32 -PassThru
# $api::SHGetDiskFreeSpaceExW(pszDirectoryName, pulFreeBytesAvailableToCaller, pulTotalNumberOfBytes, pulTotalNumberOfFreeBytes)

#uselib "SHELL32.dll"
#func global SHGetDiskFreeSpaceExW "SHGetDiskFreeSpaceExW" wptr, wptr, wptr, wptr
; SHGetDiskFreeSpaceExW pszDirectoryName, varptr(pulFreeBytesAvailableToCaller), varptr(pulTotalNumberOfBytes), varptr(pulTotalNumberOfFreeBytes)   ; 戻り値は stat
; pszDirectoryName : LPCWSTR -> "wptr"
; pulFreeBytesAvailableToCaller : ULONGLONG* optional, out -> "wptr"
; pulTotalNumberOfBytes : ULONGLONG* optional, out -> "wptr"
; pulTotalNumberOfFreeBytes : ULONGLONG* 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 "SHELL32.dll"
#cfunc global SHGetDiskFreeSpaceExW "SHGetDiskFreeSpaceExW" wstr, var, var, var
; res = SHGetDiskFreeSpaceExW(pszDirectoryName, pulFreeBytesAvailableToCaller, pulTotalNumberOfBytes, pulTotalNumberOfFreeBytes)
; pszDirectoryName : LPCWSTR -> "wstr"
; pulFreeBytesAvailableToCaller : ULONGLONG* optional, out -> "var"
; pulTotalNumberOfBytes : ULONGLONG* optional, out -> "var"
; pulTotalNumberOfFreeBytes : ULONGLONG* 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。

; BOOL SHGetDiskFreeSpaceExW(LPCWSTR pszDirectoryName, ULONGLONG* pulFreeBytesAvailableToCaller, ULONGLONG* pulTotalNumberOfBytes, ULONGLONG* pulTotalNumberOfFreeBytes)
#uselib "SHELL32.dll"
#cfunc global SHGetDiskFreeSpaceExW "SHGetDiskFreeSpaceExW" wstr, var, var, var
; res = SHGetDiskFreeSpaceExW(pszDirectoryName, pulFreeBytesAvailableToCaller, pulTotalNumberOfBytes, pulTotalNumberOfFreeBytes)
; pszDirectoryName : LPCWSTR -> "wstr"
; pulFreeBytesAvailableToCaller : ULONGLONG* optional, out -> "var"
; pulTotalNumberOfBytes : ULONGLONG* optional, out -> "var"
; pulTotalNumberOfFreeBytes : ULONGLONG* 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 (
	shell32 = windows.NewLazySystemDLL("SHELL32.dll")
	procSHGetDiskFreeSpaceExW = shell32.NewProc("SHGetDiskFreeSpaceExW")
)

// pszDirectoryName (LPCWSTR), pulFreeBytesAvailableToCaller (ULONGLONG* optional, out), pulTotalNumberOfBytes (ULONGLONG* optional, out), pulTotalNumberOfFreeBytes (ULONGLONG* optional, out)
r1, _, err := procSHGetDiskFreeSpaceExW.Call(
	uintptr(unsafe.Pointer(windows.StringToUTF16Ptr(pszDirectoryName))),
	uintptr(pulFreeBytesAvailableToCaller),
	uintptr(pulTotalNumberOfBytes),
	uintptr(pulTotalNumberOfFreeBytes),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // BOOL

function SHGetDiskFreeSpaceExW(
  pszDirectoryName: PWideChar;   // LPCWSTR
  pulFreeBytesAvailableToCaller: Pointer;   // ULONGLONG* optional, out
  pulTotalNumberOfBytes: Pointer;   // ULONGLONG* optional, out
  pulTotalNumberOfFreeBytes: Pointer   // ULONGLONG* optional, out
): BOOL; stdcall;
  external 'SHELL32.dll' name 'SHGetDiskFreeSpaceExW';

result := DllCall("SHELL32\SHGetDiskFreeSpaceExW"
    , "WStr", pszDirectoryName   ; LPCWSTR
    , "Ptr", pulFreeBytesAvailableToCaller   ; ULONGLONG* optional, out
    , "Ptr", pulTotalNumberOfBytes   ; ULONGLONG* optional, out
    , "Ptr", pulTotalNumberOfFreeBytes   ; ULONGLONG* optional, out
    , "Int")   ; return: BOOL

●SHGetDiskFreeSpaceExW(pszDirectoryName, pulFreeBytesAvailableToCaller, pulTotalNumberOfBytes, pulTotalNumberOfFreeBytes) = DLL("SHELL32.dll", "bool SHGetDiskFreeSpaceExW(char*, void*, void*, void*)")
# 呼び出し: SHGetDiskFreeSpaceExW(pszDirectoryName, pulFreeBytesAvailableToCaller, pulTotalNumberOfBytes, pulTotalNumberOfFreeBytes)
# pszDirectoryName : LPCWSTR -> "char*"
# pulFreeBytesAvailableToCaller : ULONGLONG* optional, out -> "void*"
# pulTotalNumberOfBytes : ULONGLONG* optional, out -> "void*"
# pulTotalNumberOfFreeBytes : ULONGLONG* optional, 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)。
# ※-W(Unicode)関数。なでしこ1はANSIのため -A 版の利用を推奨。