# The WebAssembly binary file decoder in Rust
**A [Bytecode Alliance](https://bytecodealliance.org/) project**
[![crates.io link](https://img.shields.io/crates/v/wasmparser.svg)](https://crates.io/crates/wasmparser)
[![docs.rs docs](https://img.shields.io/static/v1?label=docs&message=wasmparser&color=blue&style=flat-square)](https://docs.rs/wasmparser/)
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 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.
[cargo-fuzz]: https://github.com/rust-fuzz/cargo-fuzz