GetEnvironmentVariableA

// KERNEL32.dll  (ANSI / -A)
#include <windows.h>

DWORD GetEnvironmentVariableA(
    LPCSTR lpName,   // optional
    LPSTR lpBuffer,   // optional
    DWORD nSize
);

<DllImport("KERNEL32.dll", CharSet:=CharSet.Ansi, SetLastError:=True, ExactSpelling:=True)>
Public Shared Function GetEnvironmentVariableA(
    <MarshalAs(UnmanagedType.LPStr)> lpName As String,   ' LPCSTR optional
    <MarshalAs(UnmanagedType.LPStr)> lpBuffer As System.Text.StringBuilder,   ' LPSTR optional, out
    nSize As UInteger   ' DWORD
) As UInteger
End Function

' lpName : LPCSTR optional
' lpBuffer : LPSTR optional, out
' nSize : DWORD
Declare PtrSafe Function GetEnvironmentVariableA Lib "kernel32" ( _
    ByVal lpName As String, _
    ByVal lpBuffer As String, _
    ByVal nSize As Long) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

GetEnvironmentVariableA = ctypes.windll.kernel32.GetEnvironmentVariableA
GetEnvironmentVariableA.restype = wintypes.DWORD
GetEnvironmentVariableA.argtypes = [
    wintypes.LPCSTR,  # lpName : LPCSTR optional
    wintypes.LPSTR,  # lpBuffer : LPSTR 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')
GetEnvironmentVariableA = Fiddle::Function.new(
  lib['GetEnvironmentVariableA'],
  [
    Fiddle::TYPE_VOIDP,  # lpName : LPCSTR optional
    Fiddle::TYPE_VOIDP,  # lpBuffer : LPSTR optional, out
    -Fiddle::TYPE_INT,  # nSize : DWORD
  ],
  -Fiddle::TYPE_INT)

#[link(name = "kernel32")]
extern "system" {
    fn GetEnvironmentVariableA(
        lpName: *const u8,  // LPCSTR optional
        lpBuffer: *mut u8,  // LPSTR optional, out
        nSize: u32  // DWORD
    ) -> u32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("KERNEL32.dll", CharSet = CharSet.Ansi, SetLastError = true)]
public static extern uint GetEnvironmentVariableA([MarshalAs(UnmanagedType.LPStr)] string lpName, [MarshalAs(UnmanagedType.LPStr)] System.Text.StringBuilder lpBuffer, uint nSize);
"@
$api = Add-Type -MemberDefinition $sig -Name 'KERNEL32_GetEnvironmentVariableA' -Namespace Win32 -PassThru
# $api::GetEnvironmentVariableA(lpName, lpBuffer, nSize)

#uselib "KERNEL32.dll"
#func global GetEnvironmentVariableA "GetEnvironmentVariableA" sptr, sptr, sptr
; GetEnvironmentVariableA lpName, varptr(lpBuffer), nSize   ; 戻り値は stat
; lpName : LPCSTR optional -> "sptr"
; lpBuffer : LPSTR optional, out -> "sptr"
; nSize : DWORD -> "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。

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

var (
	kernel32 = windows.NewLazySystemDLL("KERNEL32.dll")
	procGetEnvironmentVariableA = kernel32.NewProc("GetEnvironmentVariableA")
)

// lpName (LPCSTR optional), lpBuffer (LPSTR optional, out), nSize (DWORD)
r1, _, err := procGetEnvironmentVariableA.Call(
	uintptr(unsafe.Pointer(windows.BytePtrFromString(lpName))),
	uintptr(lpBuffer),
	uintptr(nSize),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // DWORD

function GetEnvironmentVariableA(
  lpName: PAnsiChar;   // LPCSTR optional
  lpBuffer: PAnsiChar;   // LPSTR optional, out
  nSize: DWORD   // DWORD
): DWORD; stdcall;
  external 'KERNEL32.dll' name 'GetEnvironmentVariableA';

result := DllCall("KERNEL32\GetEnvironmentVariableA"
    , "AStr", lpName   ; LPCSTR optional
    , "Ptr", lpBuffer   ; LPSTR optional, out
    , "UInt", nSize   ; DWORD
    , "UInt")   ; return: DWORD

●GetEnvironmentVariableA(lpName, lpBuffer, nSize) = DLL("KERNEL32.dll", "dword GetEnvironmentVariableA(char*, char*, dword)")
# 呼び出し: GetEnvironmentVariableA(lpName, lpBuffer, nSize)
# lpName : LPCSTR optional -> "char*"
# lpBuffer : LPSTR 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)。

const std = @import("std");

extern "kernel32" fn GetEnvironmentVariableA(
    lpName: [*c]const u8, // LPCSTR optional
    lpBuffer: [*c]u8, // LPSTR optional, out
    nSize: u32 // DWORD
) callconv(std.os.windows.WINAPI) u32;

proc GetEnvironmentVariableA(
    lpName: cstring,  # LPCSTR optional
    lpBuffer: ptr char,  # LPSTR optional, out
    nSize: uint32  # DWORD
): uint32 {.importc: "GetEnvironmentVariableA", stdcall, dynlib: "KERNEL32.dll".}

pragma(lib, "kernel32");
extern(Windows)
uint GetEnvironmentVariableA(
    const(char)* lpName,   // LPCSTR optional
    char* lpBuffer,   // LPSTR optional, out
    uint nSize   // DWORD
);

ccall((:GetEnvironmentVariableA, "KERNEL32.dll"), stdcall, UInt32,
      (Cstring, Ptr{UInt8}, UInt32),
      lpName, lpBuffer, nSize)
# lpName : LPCSTR optional -> Cstring
# lpBuffer : LPSTR optional, out -> Ptr{UInt8}
# nSize : DWORD -> UInt32
# stdcall は 32bit のみ意味を持つ(x64 では無視)。

local ffi = require("ffi")
ffi.cdef[[
uint32_t GetEnvironmentVariableA(
    const char* lpName,
    char* lpBuffer,
    uint32_t nSize);
]]
local kernel32 = ffi.load("kernel32")
-- kernel32.GetEnvironmentVariableA(lpName, lpBuffer, nSize)
-- lpName : LPCSTR optional
-- lpBuffer : LPSTR optional, out
-- nSize : DWORD
-- 構造体/GUIDへのポインタは cdef が通るよう void* で表記(実型は各引数コメント参照)。値渡し構造体・enum は対応する typedef を cdef に追加すること。

const koffi = require('koffi');
const lib = koffi.load('KERNEL32.dll');
const GetEnvironmentVariableA = lib.func('__stdcall', 'GetEnvironmentVariableA', 'uint32_t', ['str', 'char *', 'uint32_t']);
// GetEnvironmentVariableA(lpName, lpBuffer, nSize)
// lpName : LPCSTR optional -> 'str'
// lpBuffer : LPSTR optional, out -> 'char *'
// nSize : DWORD -> 'uint32_t'
// 出力ポインタは koffi.out(...) で包む。構造体は koffi.struct で定義。

const lib = Deno.dlopen("KERNEL32.dll", {
  GetEnvironmentVariableA: { parameters: ["buffer", "buffer", "u32"], result: "u32" },
});
// lib.symbols.GetEnvironmentVariableA(lpName, lpBuffer, nSize)
// lpName : LPCSTR optional -> "buffer"
// lpBuffer : LPSTR optional, out -> "buffer"
// nSize : DWORD -> "u32"
// 文字列は "buffer"。ANSI(-A) は new TextEncoder() で UTF-8/ANSI バイト列(末尾に \x00)を渡す。
// 値渡し構造体は { struct: [ ...field types... ] } を使用。

<?php
$ffi = FFI::cdef(<<<C
uint32_t GetEnvironmentVariableA(
    const char* lpName,
    char* lpBuffer,
    uint32_t nSize);
C, "KERNEL32.dll");
// $ffi->GetEnvironmentVariableA(lpName, lpBuffer, nSize);
// lpName : LPCSTR optional
// lpBuffer : LPSTR optional, out
// nSize : DWORD
// 構造体/GUIDへのポインタは cdef が通るよう void* で表記(実型は各引数コメント参照)。値渡し構造体・enum は対応する typedef を cdef に追加すること。
// WINAPI(stdcall): x64 では呼出規約が統一されるため問題なし。x86 では __stdcall 対応のラッパが必要な場合あり。

import com.sun.jna.*;
import com.sun.jna.ptr.*;
import com.sun.jna.win32.StdCallLibrary;
import com.sun.jna.win32.W32APIOptions;

public interface Kernel32 extends StdCallLibrary {
    Kernel32 INSTANCE = Native.load("kernel32", Kernel32.class, W32APIOptions.ASCII_OPTIONS);
    int GetEnvironmentVariableA(
        String lpName,   // LPCSTR optional
        byte[] lpBuffer,   // LPSTR optional, out
        int nSize   // DWORD
    );
}

@[Link("kernel32")]
lib LibKERNEL32
  fun GetEnvironmentVariableA = GetEnvironmentVariableA(
    lpName : UInt8*,   # LPCSTR optional
    lpBuffer : UInt8*,   # LPSTR optional, out
    nSize : UInt32   # DWORD
  ) : UInt32
end
# 構造体/GUID/enum は lib 内に対応する型定義が必要。
# 呼出規約: x64 は規約統一のため OK。x86(32bit)は WINAPI=stdcall だが Crystal の fun に stdcall 付与構文がなく非対応。

import 'dart:ffi';
import 'package:ffi/ffi.dart';

typedef GetEnvironmentVariableANative = Uint32 Function(Pointer<Utf8>, Pointer<Utf8>, Uint32);
typedef GetEnvironmentVariableADart = int Function(Pointer<Utf8>, Pointer<Utf8>, int);
final GetEnvironmentVariableA = DynamicLibrary.open('KERNEL32.dll')
    .lookupFunction<GetEnvironmentVariableANative, GetEnvironmentVariableADart>('GetEnvironmentVariableA');
// lpName : LPCSTR optional -> Pointer<Utf8>
// lpBuffer : LPSTR optional, out -> Pointer<Utf8>
// nSize : DWORD -> Uint32
// 文字列は package:ffi の "...".toNativeUtf16()/toNativeUtf8() で変換。

{$mode objfpc}{$H+}
function GetEnvironmentVariableA(
  lpName: PAnsiChar;   // LPCSTR optional
  lpBuffer: PAnsiChar;   // LPSTR optional, out
  nSize: DWORD   // DWORD
): DWORD; stdcall;
  external 'KERNEL32.dll' name 'GetEnvironmentVariableA';

import Foreign
import Foreign.C.Types
import Foreign.C.String

foreign import stdcall safe "GetEnvironmentVariableA"
  c_GetEnvironmentVariableA :: CString -> CString -> Word32 -> IO Word32
-- lpName : LPCSTR optional -> CString
-- lpBuffer : LPSTR optional, out -> CString
-- nSize : DWORD -> Word32
-- 要 GHC(Windows)。stdcall は x64 では ccall として扱われる。ブロックする API は safe 呼び出し推奨。

open Ctypes
open Foreign

let getenvironmentvariablea =
  foreign "GetEnvironmentVariableA"
    (string @-> string @-> uint32_t @-> returning uint32_t)
(* lpName : LPCSTR optional -> string *)
(* lpBuffer : LPSTR optional, out -> string *)
(* nSize : DWORD -> uint32_t *)
(* foreign は cdecl 前提。x64 Windows では WINAPI と一致。構造体は ctypes structure を定義のこと。 *)

(cffi:define-foreign-library kernel32 (t "KERNEL32.dll"))
(cffi:use-foreign-library kernel32)

(cffi:defcfun ("GetEnvironmentVariableA" get-environment-variable-a :convention :stdcall) :uint32
  (lp-name :string)   ; LPCSTR optional
  (lp-buffer :pointer)   ; LPSTR optional, out
  (n-size :uint32))   ; DWORD
; isize/usize(INT_PTR/SIZE_T)は x64 前提で :int64/:uint64。x86 では :int32/:uint32。

use Win32::API;
my $GetEnvironmentVariableA = Win32::API::More->new('KERNEL32',
    'DWORD GetEnvironmentVariableA(LPCSTR lpName, LPSTR lpBuffer, DWORD nSize)');
# my $ret = $GetEnvironmentVariableA->Call($lpName, $lpBuffer, $nSize);
# lpName : LPCSTR optional -> LPCSTR
# lpBuffer : LPSTR optional, out -> LPSTR
# nSize : DWORD -> DWORD
# 値渡し構造体は pack() した文字列、または Win32::API::Struct を使用。