The WebAssembly binary file decoder in Rust

A Bytecode Alliance project

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

```rust use wasmparser::WasmDecoder; use wasmparser::Parser; use wasmparser::ParserState;

fn getname(bytes: &[u8]) -> &str { str::fromutf8(bytes).ok().unwrap() }

fn main() { let ref buf: Vec = readwasmbytes(); 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.