![Wasker_logo](./doc/assets/wasker.png "Wasker_logo")

# Wasker

Wasker is a WebAssembly compiler.
Wasker compiles Wasm binary into ELF format binary.　
Currently, Wasker supports WASI preview 1.

![Wasker_architecture](./doc/assets/wasker_architecture.png "Wasker_architecture")

## What's new with Wasker

There are already software tools that compile Wasm to native binaries.

What's new with Wasker is, Wasker generates an **OS-independent** ELF file where WASI calls from Wasm applications remain **unresolved**.

This unresolved feature allows Wasker's output ELF file to be **linked with WASI implementations provided by various operating systems**, enabling each OS to execute Wasm applications.

Wasker empowers your favorite OS to serve as a Wasm runtime!

![demo](./doc/assets/wasker.gif)


# Installation
Wasker compiler is based on LLVM (LLVM 15 currently).

Suppose `cargo` is installed.

```
export LLVM_SYS_150_PREFIX=~/.wasker/clang+llvm-15.0.0-x86_64-linux-gnu-rhel-8.4/
cargo install wasker
```

# Run Wasker

## Step1: Prepare Wasm binary
Please refer [examples](./examples) for building Wasm from Rust and Go. 

```
cd examples/rust
rustup target add wasm32-wasi
cargo build --target wasm32-wasi
```

## Step2: Run Wasker
```
$ wasker examples/rust/target/wasm32-wasi/debug/rust.wasm
[2024-03-19T12:10:20Z INFO  wasker::compiler] input: examples/rust/target/wasm32-wasi/debug/rust.wasm
[2024-03-19T12:10:20Z INFO  wasker::compiler] write to ./wasm.ll
[2024-03-19T12:10:20Z INFO  wasker::compiler] write to ./wasm.o, it may take a while
[2024-03-19T12:10:21Z INFO  wasker::compiler] Compile success
```

## Step3: Run wasker output on Linux

ELF file generated by Wasker is OS-independent: WASI calls from Wasm applications remain unresolved.

Please write your own WASI wrapper for your favorite OS to be linked with Wasker output.

Here, we'll show a [tiny example](./examples/wasi-wrapper/wasi-wrapper-linux.c) of running Wasker output on Linux.

Compile WASI wapper for Linux and ink with Wasker output. 
```
gcc -no-pie ./examples/wasi-wrapper/wasi-wrapper-linux.c ./wasm.o -o hello
```

Run!!
```
./hello
```

Also please check [Mewz](https://github.com/Mewz-project/Mewz.git), a unikernel OS which has WASI interface. 
ELF file generated by Wasker can be executed on Mewz without any modification.


# Development

## Option1 : Use Devcontainer
You can try Wasker via Devcontainer.

## Option2 : Build from source
```
git clone git@github.com:mewz-project/wasker.git
cd Wasker
export LLVM_SYS_150_PREFIX=~/.wasker/clang+llvm-15.0.0-x86_64-linux-gnu-rhel-8.4/
cargo install wasker
```
By default, Wasker targets x86_64. If you want to target AArch64, please rewrite [build.rs](./build.rs) and override `LLVM_SYS_150_PREFIX` environment variable as follows.

```rust
# build.rs
5: let target = format!("clang+llvm-{}-aarch64-linux-gnu-rhel-8.4", llvm_version);

# shell
export LLVM_SYS_150_PREFIX=~/.wasker/clang+llvm-15.0.0-aarch64-linux-gnu/
```