#parser #WebAssembly #wasm

wasmparser

A simple event-driven library for parsing WebAssembly binary files

119 releases (56 breaking)

✓ Uses Rust 2018 edition

0.57.0 May 22, 2020
0.55.0 May 12, 2020
0.51.4 Feb 27, 2020
0.45.0 Dec 17, 2019
0.7.2 Jul 7, 2017

#2 in WebAssembly

Download history 8816/week @ 2020-02-09 11664/week @ 2020-02-16 14091/week @ 2020-02-23 14451/week @ 2020-03-01 16025/week @ 2020-03-08 12176/week @ 2020-03-15 13220/week @ 2020-03-22 13136/week @ 2020-03-29 11800/week @ 2020-04-05 14139/week @ 2020-04-12 16085/week @ 2020-04-19 14092/week @ 2020-04-26 13596/week @ 2020-05-03 19524/week @ 2020-05-10 17623/week @ 2020-05-17 16236/week @ 2020-05-24

62,960 downloads per month
Used in 110 crates (32 directly)

Apache-2.0 WITH LLVM-exception

380KB
9K SLoC

Ruby HTML 9K SLoC // 0.1% comments Scons 5 SLoC // 0.4% comments

The WebAssembly binary file decoder in Rust

A Bytecode Alliance project

crates.io link docs.rs docs

The decoder library provides lightweight and fast decoding/parsing of WebAssembly binary files.

The other goal is minimal memory footprint. For this reason, there is no AST or IR of WebAssembly data.

See also its sibling at https://github.com/wasdk/wasmparser

Documentation

The documentation and examples can be found at the https://docs.rs/wasmparser/

Example

use wasmparser::WasmDecoder;
use wasmparser::Parser;
use wasmparser::ParserState;

fn get_name(bytes: &[u8]) -> &str {
  str::from_utf8(bytes).ok().unwrap()
}

fn main() {
  let ref buf: Vec<u8> = read_wasm_bytes();
  let mut parser = Parser::new(buf);
  loop {
    let state = parser.read();
    match *state {
        ParserState::BeginWasm { .. } => {
            println!("====== Module");
        }
        ParserState::ExportSectionEntry { field, ref kind, .. } => {
            println!("  Export {} {:?}", get_name(field), kind);
        }
        ParserState::ImportSectionEntry { module, field, .. } => {
            println!("  Import {}::{}", get_name(module), get_name(field))
        }
        ParserState::EndWasm => break,
        _ => ( /* println!(" Other {:?}", state) */ )
    }
  }
}

Fuzzing

To fuzz test wasmparser.rs, switch to a nightly Rust compiler and install cargo-fuzz:

cargo install cargo-fuzz

Then, from the root of the repository, run:

cargo fuzz run parse

If you want to use files as seeds for the fuzzer, add them to fuzz/corpus/parse/ and restart cargo-fuzz.

No runtime deps