ELF Parser

A TypeScript library for parsing ELF binaries and resolving DWARF line information for symbol addresses.

Features

• Parse ELF headers, sections, and symbol tables
• Resolve machine and type metadata from ELF headers
• Map symbol addresses back to source file and line numbers using DWARF data
• Expose a Node-friendly TypeScript API
• Build a Rust-backed WebAssembly implementation for fast symbol lookup

Project layout

• src/index.ts - TypeScript entry point for the package
• lib/ - generated JavaScript and declaration output
• wasm-elf-parser/ - Rust crate that produces the WebAssembly parser
• .github/workflows/build.yml - CI build workflow

Prerequisites

• Node.js 22+

Install

npm install

The published package includes the generated WASM files, so installing it does not require Rust.

Build prerequisites

Building the WASM implementation from source requires:

• Rust toolchain with the wasm32-unknown-unknown target
• wasm-bindgen-cli

Build

npm run build

The build does the following:

1. Compiles the Rust WASM library
2. Generates JavaScript and TypeScript bindings with wasm-bindgen
3. Compiles the TypeScript package into lib/

Package usage

After building, the package entry point is:

const { ElfParser } = require("elfparser");

or in TypeScript:

import { ElfParser } from "elfparser";

Example

import { readFileSync } from "node:fs";
import { ElfParser } from "elfparser";

const file = readFileSync("path/to/binary");
const parser = new ElfParser(file);

console.log(parser.header);
console.log(parser.getSymbols());

Unnamed symbols

getSymbols() includes all entries from the ELF symbol tables, including entries without a name. These entries can still be useful when inspecting ELF metadata:

• The first entry is the mandatory ELF null symbol. It has no name and a zero value.
• Unnamed STT_SECTION entries identify sections and can be useful for low-level inspection, relocation, or debugging.

For application-level symbol lookup, filter out unnamed entries. To find functions, filter by symbol type as well:

const namedSymbols = parser.getSymbols().filter((symbol) => symbol.name !== "");

const functions = parser
    .getSymbols()
    .filter(
        (symbol) =>
            symbol.name !== "" &&
            (symbol.type === "STT_FUNC" || symbol.type === "STT_NOTYPE"),
    );

License

ISC