GetEnvironmentVariableW

// KERNEL32.dll  (Unicode / -W)
#include <windows.h>

DWORD GetEnvironmentVariableW(
    LPCWSTR lpName,   // optional
    LPWSTR lpBuffer,   // optional
    DWORD nSize
);

<DllImport("KERNEL32.dll", CharSet:=CharSet.Unicode, SetLastError:=True, ExactSpelling:=True)>
Public Shared Function GetEnvironmentVariableW(
    <MarshalAs(UnmanagedType.LPWStr)> lpName As String,   ' LPCWSTR optional
    <MarshalAs(UnmanagedType.LPWStr)> lpBuffer As System.Text.StringBuilder,   ' LPWSTR optional, out
    nSize As UInteger   ' DWORD
) As UInteger
End Function

' lpName : LPCWSTR optional
' lpBuffer : LPWSTR optional, out
' nSize : DWORD
Declare PtrSafe Function GetEnvironmentVariableW Lib "kernel32" ( _
    ByVal lpName As LongPtr, _
    ByVal lpBuffer As LongPtr, _
    ByVal nSize As Long) 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

GetEnvironmentVariableW = ctypes.windll.kernel32.GetEnvironmentVariableW
GetEnvironmentVariableW.restype = wintypes.DWORD
GetEnvironmentVariableW.argtypes = [
    wintypes.LPCWSTR,  # lpName : LPCWSTR optional
    wintypes.LPWSTR,  # lpBuffer : LPWSTR optional, out
    wintypes.DWORD,  # nSize : DWORD
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('KERNEL32.dll')
GetEnvironmentVariableW = Fiddle::Function.new(
  lib['GetEnvironmentVariableW'],
  [
    Fiddle::TYPE_VOIDP,  # lpName : LPCWSTR optional
    Fiddle::TYPE_VOIDP,  # lpBuffer : LPWSTR optional, out
    -Fiddle::TYPE_INT,  # nSize : DWORD
  ],
  -Fiddle::TYPE_INT)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

#[link(name = "kernel32")]
extern "system" {
    fn GetEnvironmentVariableW(
        lpName: *const u16,  // LPCWSTR optional
        lpBuffer: *mut u16,  // LPWSTR optional, out
        nSize: u32  // DWORD
    ) -> u32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("KERNEL32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern uint GetEnvironmentVariableW([MarshalAs(UnmanagedType.LPWStr)] string lpName, [MarshalAs(UnmanagedType.LPWStr)] System.Text.StringBuilder lpBuffer, uint nSize);
"@
$api = Add-Type -MemberDefinition $sig -Name 'KERNEL32_GetEnvironmentVariableW' -Namespace Win32 -PassThru
# $api::GetEnvironmentVariableW(lpName, lpBuffer, nSize)

#uselib "KERNEL32.dll"
#func global GetEnvironmentVariableW "GetEnvironmentVariableW" wptr, wptr, wptr
; GetEnvironmentVariableW lpName, varptr(lpBuffer), nSize   ; 戻り値は stat
; lpName : LPCWSTR optional -> "wptr"
; lpBuffer : LPWSTR optional, out -> "wptr"
; nSize : DWORD -> "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 "KERNEL32.dll"
#cfunc global GetEnvironmentVariableW "GetEnvironmentVariableW" wstr, var, int
; res = GetEnvironmentVariableW(lpName, lpBuffer, nSize)
; lpName : LPCWSTR optional -> "wstr"
; lpBuffer : LPWSTR optional, out -> "var"
; nSize : DWORD -> "int"
; ※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 GetEnvironmentVariableW(LPCWSTR lpName, LPWSTR lpBuffer, DWORD nSize)
#uselib "KERNEL32.dll"
#cfunc global GetEnvironmentVariableW "GetEnvironmentVariableW" wstr, var, int
; res = GetEnvironmentVariableW(lpName, lpBuffer, nSize)
; lpName : LPCWSTR optional -> "wstr"
; lpBuffer : LPWSTR optional, out -> "var"
; nSize : DWORD -> "int"
; ※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 (
	kernel32 = windows.NewLazySystemDLL("KERNEL32.dll")
	procGetEnvironmentVariableW = kernel32.NewProc("GetEnvironmentVariableW")
)

// lpName (LPCWSTR optional), lpBuffer (LPWSTR optional, out), nSize (DWORD)
r1, _, err := procGetEnvironmentVariableW.Call(
	uintptr(unsafe.Pointer(windows.StringToUTF16Ptr(lpName))),
	uintptr(lpBuffer),
	uintptr(nSize),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // DWORD

function GetEnvironmentVariableW(
  lpName: PWideChar;   // LPCWSTR optional
  lpBuffer: PWideChar;   // LPWSTR optional, out
  nSize: DWORD   // DWORD
): DWORD; stdcall;
  external 'KERNEL32.dll' name 'GetEnvironmentVariableW';

result := DllCall("KERNEL32\GetEnvironmentVariableW"
    , "WStr", lpName   ; LPCWSTR optional
    , "Ptr", lpBuffer   ; LPWSTR optional, out
    , "UInt", nSize   ; DWORD
    , "UInt")   ; return: DWORD

●GetEnvironmentVariableW(lpName, lpBuffer, nSize) = DLL("KERNEL32.dll", "dword GetEnvironmentVariableW(char*, char*, dword)")
# 呼び出し: GetEnvironmentVariableW(lpName, lpBuffer, nSize)
# lpName : LPCWSTR optional -> "char*"
# lpBuffer : LPWSTR optional, out -> "char*"
# nSize : DWORD -> "dword"
# 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。