#parser #WebAssembly #wasm

wasmparser

A simple event-driven library for parsing WebAssembly binary files

111 releases (50 breaking)

✓ Uses Rust 2018 edition

0.51.4 Feb 27, 2020
0.50.0 Feb 5, 2020
0.45.0 Dec 17, 2019
0.42.1 Nov 18, 2019
0.7.2 Jul 7, 2017

#2 in WebAssembly

Download history 9106/week @ 2019-12-02 10231/week @ 2019-12-09 9538/week @ 2019-12-16 3663/week @ 2019-12-23 4232/week @ 2019-12-30 14434/week @ 2020-01-06 15401/week @ 2020-01-13 9944/week @ 2020-01-20 6450/week @ 2020-01-27 11230/week @ 2020-02-03 8829/week @ 2020-02-10 11525/week @ 2020-02-17 14121/week @ 2020-02-24 14474/week @ 2020-03-02 15942/week @ 2020-03-09 11931/week @ 2020-03-16

41,545 downloads per month
Used in 101 crates (33 directly)

Apache-2.0 WITH LLVM-exception

390KB
9K SLoC

The WebAssembly binary file decoder in Rust

A Bytecode Alliance project

CI crates.io link

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