@bun-win32/rpcrt4

Zero-dependency, zero-overhead Win32 RPCRT4 bindings for Bun on Windows.

Overview

@bun-win32/rpcrt4 exposes the rpcrt4.dll exports using Bun's FFI. It provides a single class, Rpcrt4, which lazily binds native symbols on first use. You can optionally preload a subset or all symbols up-front via Preload().

The bindings are strongly typed for a smooth DX in TypeScript.

Features

• Bun-first ergonomics on Windows 10/11.
• Direct FFI to rpcrt4.dll (UUID generation, RPC client/server, string bindings, endpoint mapping, authentication, error enumeration, and MES pickling).
• In-source docs in structs/Rpcrt4.ts with links to Microsoft Docs.
• Lazy binding on first call; optional eager preload (Rpcrt4.Preload()).
• No wrapper overhead; calls map 1:1 to native APIs.
• Strongly-typed Win32 aliases (see types/Rpcrt4.ts).

Requirements

• Bun runtime
• Windows 10 or later

Installation

bun add @bun-win32/rpcrt4

Quick Start

import Rpcrt4 from '@bun-win32/rpcrt4';
import { read, toArrayBuffer, type Pointer } from 'bun:ffi';

// Generate a fresh UUID
const uuid = Buffer.alloc(16);
Rpcrt4.UuidCreate(uuid.ptr!);

// Convert to canonical string form
const stringOut = Buffer.alloc(8);
Rpcrt4.UuidToStringW(uuid.ptr!, stringOut.ptr!);
const strPtr = read.ptr(stringOut.ptr!) as Pointer;
const text = new TextDecoder('utf-16').decode(toArrayBuffer(strPtr, 0, 80)).replace(/\0.*$/, '');
console.log(text); // e.g. 7e8f0c30-1d8a-4b7e-9f12-2c3d4e5f6789

// Free the wide string when done
Rpcrt4.RpcStringFreeW(stringOut.ptr!);

[!NOTE] AI agents: see AI.md for the package binding contract and source-navigation guidance. It explains how to use the package without scanning the entire implementation.

Examples

Run the included examples:

bun run example:uuid-cascade
bun run example:rpc-diagnostic

Notes

• Either rely on lazy binding or call Rpcrt4.Preload().
• Windows only. Bun runtime required.
• SAL types & naming: nullability is in the type — Optional<T> (formally optional, SAL _*opt_) and Nullable<T> (plain [in]/[out] the docs say can be NULL), the null sentinel derived from T (null for pointers LP*/P*, 0n for handles/by-value addresses); direction is in the parameter name — _out (_Out_), _in_out (_Inout_), _In_ bare. See AI.md and the repo AGENTS.md.