FFI

import { dlopen, FFIType, suffix } from "bun:ffi";

// `suffix` is either "dylib", "so", or "dll" depending on the platform
// you don't have to use "suffix", it's just there for convenience
const path = `libsqlite3.${suffix}`;

const {
  symbols: {
    sqlite3_libversion, // the function to call
  },
} = dlopen(
  path, // a library name or file path
  {
    sqlite3_libversion: {
      // no arguments, returns a string
      args: [],
      returns: FFIType.cstring,
    },
  },
);

console.log(`SQLite 3 version: ${sqlite3_libversion()}`);

// add.zig
pub export fn add(a: i32, b: i32) i32 {
  return a + b;
}

import { dlopen, FFIType, suffix } from "bun:ffi";
const { i32 } = FFIType;

const path = `libadd.${suffix}`;

const lib = dlopen(path, {
  add: {
    args: [i32, i32],
    returns: i32,
  },
});

console.log(lib.symbols.add(1, 2));

// add.rs
#[no_mangle]
pub extern "C" fn add(a: i32, b: i32) -> i32 {
    a + b
}

#include <cstdint>

extern "C" int32_t add(int32_t a, int32_t b) {
    return a + b;
}

class CString extends String {
  /**
   * Given a `ptr`, this will automatically search for the closing `\0` character and transcode from UTF-8 to UTF-16 if necessary.
   */
  constructor(ptr: number, byteOffset?: number, byteLength?: number): string;

  /**
   * The ptr to the C string
   *
   * This `CString` instance is a clone of the string, so it
   * is safe to continue using this instance after the `ptr` has been
   * freed.
   */
  ptr: number;
  byteOffset?: number;
  byteLength?: number;
}

const myString = new CString(ptr);

const myString = new CString(ptr, 0, byteLength);

my_library_free(myString.ptr);

// this is safe because myString is a clone
console.log(myString);

import { CFunction } from "bun:ffi";

let myNativeLibraryGetVersion = /* somehow, you got this pointer */

const getVersion = new CFunction({
  returns: "cstring",
  args: [],
  ptr: myNativeLibraryGetVersion,
});
getVersion();

import { linkSymbols } from "bun:ffi";

// getVersionPtrs defined elsewhere
const [majorPtr, minorPtr, patchPtr] = getVersionPtrs();

const lib = linkSymbols({
  // Unlike with dlopen(), the names here can be whatever you want
  getMajor: {
    returns: "cstring",
    args: [],

    // Since this doesn't use dlsym(), you have to provide a valid ptr
    // That ptr could be a number or a bigint
    // An invalid pointer will crash your program.
    ptr: majorPtr,
  },
  getMinor: {
    returns: "cstring",
    args: [],
    ptr: minorPtr,
  },
  getPatch: {
    returns: "cstring",
    args: [],
    ptr: patchPtr,
  },
});

const [major, minor, patch] = [
  lib.symbols.getMajor(),
  lib.symbols.getMinor(),
  lib.symbols.getPatch(),
];

import { dlopen, JSCallback, ptr, CString } from "bun:ffi";

const {
  symbols: { search },
  close,
} = dlopen("libmylib", {
  search: {
    returns: "usize",
    args: ["cstring", "callback"],
  },
});

const searchIterator = new JSCallback(
  (ptr, length) => /hello/.test(new CString(ptr, length)),
  {
    returns: "bool",
    args: ["ptr", "usize"],
  },
);

const str = Buffer.from("wwutwutwutwutwutwutwutwutwutwutut\0", "utf8");
if (search(ptr(str), searchIterator)) {
  // found a match!
}

// Sometime later:
setTimeout(() => {
  searchIterator.close();
  close();
}, 5000);

import { ptr } from "bun:ffi";
let myTypedArray = new Uint8Array(32);
const myPtr = ptr(myTypedArray);

import { ptr, toArrayBuffer } from "bun:ffi";
let myTypedArray = new Uint8Array(32);
const myPtr = ptr(myTypedArray);

// toArrayBuffer accepts a `byteOffset` and `byteLength`
// if `byteLength` is not provided, it is assumed to be a null-terminated pointer
myTypedArray = new Uint8Array(toArrayBuffer(myPtr, 0, 32), 0, 32);

import { toArrayBuffer } from "bun:ffi";
let myDataView = new DataView(toArrayBuffer(myPtr, 0, 32));

console.log(
  myDataView.getUint8(0, true),
  myDataView.getUint8(1, true),
  myDataView.getUint8(2, true),
  myDataView.getUint8(3, true),
);

import { read } from "bun:ffi";

console.log(
  // ptr, byteOffset
  read.u8(myPtr, 0),
  read.u8(myPtr, 1),
  read.u8(myPtr, 2),
  read.u8(myPtr, 3),
);

typedef void (*JSTypedArrayBytesDeallocator)(void *bytes, void *deallocatorContext);

import { toArrayBuffer } from "bun:ffi";

// with a deallocatorContext:
toArrayBuffer(
  bytes,
  byteOffset,

  byteLength,

  // this is an optional pointer to a callback
  deallocatorContext,

  // this is a pointer to a function
  jsTypedArrayBytesDeallocator,
);

// without a deallocatorContext:
toArrayBuffer(
  bytes,
  byteOffset,

  byteLength,

  // this is a pointer to a function
  jsTypedArrayBytesDeallocator,
);

import { dlopen, FFIType } from "bun:ffi";

const {
  symbols: { encode_png },
} = dlopen(myLibraryPath, {
  encode_png: {
    // FFIType's can be specified as strings too
    args: ["ptr", "u32", "u32"],
    returns: FFIType.ptr,
  },
});

const pixels = new Uint8ClampedArray(128 * 128 * 4);
pixels.fill(254);
pixels.subarray(0, 32 * 32 * 2).fill(0);

const out = encode_png(
  // pixels will be passed as a pointer
  pixels,

  128,
  128,
);

const out = encode_png(
  // pixels will be passed as a pointer
  pixels,

  // dimensions:
  128,
  128,
);

// assuming it is 0-terminated, it can be read like this:
let png = new Uint8Array(toArrayBuffer(out));

// save it to disk:
await Bun.write("out.png", png);