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Signed-off-by: David Calavera <david.calavera@gmail.com>
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‎.gitignore

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/target
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**/*.rs.bk
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Cargo.lock
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bin/
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pkg/
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wasm-pack.log

‎Cargo.toml

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[package]
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name = "elf-cam"
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version = "0.1.0"
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authors = ["David Calavera <david.calavera@gmail.com>"]
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edition = "2018"
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repository = "https://github.com/netlify/elf-cam"
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private = true
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license = "Apache 2"
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description = "elf-cam is a WebAssembly(WASM) module to extract very specific information from binary files built for Linux, also known as ELF files."
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[lib]
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crate-type = ["cdylib", "rlib"]
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[features]
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default = ["console_error_panic_hook"]
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[dependencies]
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wasm-bindgen = "0.2.63"
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goblin = { version = "0.2", default-features = false, features = ["elf32", "elf64", "endian_fd"] }
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# The `console_error_panic_hook` crate provides better debugging of panics by
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# logging them with `console.error`. This is great for development, but requires
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# all the `std::fmt` and `std::panicking` infrastructure, so isn't great for
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# code size when deploying.
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console_error_panic_hook = { version = "0.1.6", optional = true }
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# `wee_alloc` is a tiny allocator for wasm that is only ~1K in code size
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# compared to the default allocator's ~10K. It is slower than the default
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# allocator, however.
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#
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# Unfortunately, `wee_alloc` requires nightly Rust when targeting wasm for now.
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wee_alloc = { version = "0.4.5", optional = true }
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[dev-dependencies]
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wasm-bindgen-test = "0.3.13"
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[profile.release]
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# Tell `rustc` to optimize for small code size.
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opt-level = "s"

‎LICENSE_APACHE

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Apache License
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Version 2.0, January 2004
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http://www.apache.org/licenses/
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TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
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‎README.md

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## Introduction
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elf-cam is a WebAssembly(WASM) module to extract very specific information from binary files built for Linux, also known as ELF files.
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It's used by other Netlify projects to detect Go and Rust binaries built for Netlify Functions.
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## Usage
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```js
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import { readFile } = require("fs");
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import * as elf from "elf-cam";
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const buffer = await readFile(path);
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try {
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const runtime = elf.detect(buffer);
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switch (runtime) {
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case elf.Runtime.Go: console.log("Go binary file"); break;
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case elf.Runtime.Rust: console.log("Rust binary file"); break;
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default: console.log("Unknown binary file");
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}
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} catch (error) {
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console.log(error);
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}
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```
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## Development
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### 🛠️ Build with `wasm-pack build`
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```
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wasm-pack build --target nodejs --release
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```
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### 🎁 Publish to NPM with `wasm-pack publish`
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```
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wasm-pack publish
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```

‎src/lib.rs

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use goblin::elf::Elf;
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mod utils;
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use wasm_bindgen::prelude::*;
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// When the `wee_alloc` feature is enabled, use `wee_alloc` as the global
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// allocator.
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#[cfg(feature = "wee_alloc")]
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#[global_allocator]
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static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;
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const RUST_PERSONALITY: &str = "rust_eh_personality";
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const GO_SECTION: &str = ".note.go.buildid";
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#[wasm_bindgen]
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#[derive(Debug, PartialEq)]
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pub enum Runtime {
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Go,
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Rust,
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}
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#[wasm_bindgen(catch)]
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pub fn detect(data: &[u8]) -> Result<Option<Runtime>, JsValue> {
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utils::set_panic_hook();
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let elf = match Elf::parse(data) {
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Ok(elf) => elf,
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_ => return Ok(None),
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};
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for s in elf
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.shdr_strtab
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.to_vec()
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.map_err(|e| format!("error reading symbols: {}", e))?
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{
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if s == GO_SECTION {
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return Ok(Some(Runtime::Go));
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}
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}
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for s in elf
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.strtab
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.to_vec()
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.map_err(|e| format!("error reading sections: {}", e))?
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{
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if s == RUST_PERSONALITY {
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return Ok(Some(Runtime::Rust));
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}
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}
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Ok(None)
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}

‎src/utils.rs

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pub fn set_panic_hook() {
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// When the `console_error_panic_hook` feature is enabled, we can call the
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// `set_panic_hook` function at least once during initialization, and then
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// we will get better error messages if our code ever panics.
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//
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// For more details see
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// https://github.com/rustwasm/console_error_panic_hook#readme
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#[cfg(feature = "console_error_panic_hook")]
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console_error_panic_hook::set_once();
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}

‎tests/data/hello-world-go

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‎tests/data/hello-world-rs

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‎tests/node.rs

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#![cfg(target_arch = "wasm32")]
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extern crate wasm_bindgen_test;
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use elf_cam::*;
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use wasm_bindgen_test::*;
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wasm_bindgen_test_configure!();
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// #[wasm_bindgen_test]
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// fn test_detect_go_runtime() {
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// let buffer = std::fs::read("tests/data/hello-world-go").expect("failed to load binary file");
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// let runtime = detect_runtime(&buffer)
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// .expect("failed to detect runtime")
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// .expect("failed to return some runtime");
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// assert_eq!(Runtime::Go, runtime);
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// }
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// #[wasm_bindgen_test]
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// fn test_detect_rust_runtime() {
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// let buffer = std::fs::read("tests/data/hello-world-rs").expect("failed to load binary file");
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// let runtime = detect_runtime(&buffer)
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// .expect("failed to detect runtime")
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// .expect("failed to return some runtime");
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// assert_eq!(Runtime::Rust, runtime);
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// }

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