@bun-win32/core

Shared base class, runtime extensions, and fundamental Win32 types for @bun-win32 packages.

Overview

@bun-win32/core provides the foundation that all @bun-win32 DLL packages build on:

• Win32 base class — Abstract class that handles lazy dlopen loading and symbol memoization. Every DLL package (kernel32, user32, etc.) extends this class.
• Runtime extensions — Installs a .ptr getter on all ArrayBuffer, Buffer, DataView, and typed array prototypes, giving direct access to native pointers for Bun FFI calls.
• Win32 type aliases — Strongly-typed aliases (HANDLE, DWORD, LPVOID, BOOL, etc.) that map Win32 C types to their TypeScript equivalents.

Requirements

• Bun runtime
• Windows 10 or later

Installation

bun add @bun-win32/core

You typically do not need to install this directly — it is pulled in as a dependency of each DLL package.

[!NOTE] AI agents: see AI.md for the package contract and runtime behavior. It explains how @bun-win32/core differs from the DLL binding packages.

Usage

Extending Win32 for a new DLL

import { FFIType, type FFIFunction } from 'bun:ffi';
import { Win32 } from '@bun-win32/core';

class MyDll extends Win32 {
  protected static override name = 'mydll.dll';
  protected static override readonly Symbols = {
    MyFunction: { args: [FFIType.u32], returns: FFIType.i32 },
  } as const satisfies Record<string, FFIFunction>;

  public static MyFunction(value: number): number {
    return MyDll.Load('MyFunction')(value);
  }
}

Runtime pointer extensions

import '@bun-win32/core';

const buffer = new Uint8Array([1, 2, 3]);
nativeFunction(buffer.ptr, buffer.length);

Win32 type aliases

import type { DWORD, HANDLE, BOOL } from '@bun-win32/core';

Notes

• This package is a dependency of all @bun-win32 DLL packages.
• 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.