wamr-rust-sdk

WAMR Rust SDK

Overview

WAMR Rust SDK provides Rust language bindings for WAMR. It is the wrapper of wasm_export.h but with Rust style. It is more convenient to use WAMR in Rust with this crate.

This crate contains API used to interact with Wasm modules. You can compile modules, instantiate modules, call their export functions, etc. Plus, as an embedded of Wasm, you can provide Wasm module functionality by creating host-defined functions.

WAMR Rust SDK includes a wamr-sys crate. It will search for the WAMR runtime source in the path ../... And then uses rust-bindgen durning the build process to make a .so.

This crate has similar concepts to the WebAssembly specification.

Core concepts

Runtime. It is the environment that hosts all the wasm modules. Each process has one runtime instance.
Module. It is the compiled .wasm or .aot. It can be loaded into runtime and instantiated into instance.
Instance. It is the running instance of a module. It can be used to call export functions.
Function. It is the exported function.

WASI concepts

WASIArgs. It is used to configure the WASI environment.
- pre-open. All files and directories in the list will be opened before the .wasm or .aot loaded.
- allowed address. All ip addresses in the allowed address list will be allowed to connect with a socket.
- allowed DNS.

WAMR private concepts

loading linking instead of instantiation linking. instantiation linking is used in Wasm JS API and Wasm C API. It means that every instance has its own, maybe variant, imports. But loading linking means that all instances share the same imports.
RuntimeArg. Control runtime behavior.
- running mode.
- allocator.
NativeFunction.
WasmValues.

Examples

Example: to run a wasm32-wasip1 .wasm

wasm32-wasip1 is a most common target for Wasm. It means that the .wasm is compiled with cargo build --target wasm32-wasip1 or wasi-sdk/bin/clang --target wasm32-wasip1.

Say there is a gcd_wasm32_wasi.wasm which includes a function named gcd. It returns the GCD of two parameters.

The rust code to call the function would be:

use wamr_rust_sdk::{
    runtime::Runtime, module::Module, instance::Instance, function::Function,
    value::WasmValue, RuntimeError
};
use std::path::PathBuf;

fn main() -> Result<(), RuntimeError> {
    let runtime = Runtime::new()?;

    let mut d = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
    d.push("resources/test");
    d.push("gcd_wasm32_wasi.wasm");

    let module = Module::from_file(&runtime, d.as_path())?;

    let instance = Instance::new(&runtime, &module, 1024 * 64)?;

    let function = Function::find_export_func(&instance, "gcd")?;

    let params: Vec<WasmValue> = vec![WasmValue::I32(9), WasmValue::I32(27)];
    let result = function.call(&instance, &params)?;
    assert_eq!(result, WasmValue::I32(9));

    Ok(())
}

Example: more configuration for runtime

With more configuration, runtime is capable to run .wasm with variant features, like

Wasm without WASI requirement. Usually, it means that the .wasm is compiled with -nostdlib or --target wasm32-unknown-unknown
Configure runtime.
Provides host-defined functions to meet import requirements.

Say there is an add_extra_wasm32_wasi.wasm. Its exported function, add(), requires an imported function, extra(), during the execution. The add() adds two parameters and the result of extra() . It is like a + b + extra().

The rust code to call the add function is like this:

use wamr_rust_sdk::{
    runtime::Runtime, module::Module, instance::Instance, function::Function,
    value::WasmValue, RuntimeError
};
use std::path::PathBuf;
use std::ffi::c_void;

extern "C" fn extra() -> i32 {
    100
}

fn main() -> Result<(), RuntimeError> {
    let runtime = Runtime::builder()
        .use_system_allocator()
        .register_host_function("extra", extra as *mut c_void)
        .build()?;

    let mut d = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
    d.push("resources/test");
    d.push("add_extra_wasm32_wasi.wasm");
    let module = Module::from_file(&runtime, d.as_path())?;

    let instance = Instance::new(&runtime, &module, 1024 * 64)?;

    let function = Function::find_export_func(&instance, "add")?;

    let params: Vec<WasmValue> = vec![WasmValue::I32(9), WasmValue::I32(27)];
    let result = function.call(&instance, &params)?;
    assert_eq!(result, WasmValue::I32(136));

    Ok(())
}

Build Instructions

Building `wamr-sys` and `wamr-rust-sdk`

To build the wamr-sys and wamr-rust-sdk crates, follow these steps:

Ensure you have the Rust toolchain installed.

Clone the repository:

git clone https://github.com/bytecodealliance/wamr-rust-sdk.git
cd wamr-rust-sdk

Build the wamr-sys crate:
```
cargo build -p wamr-sys
```
Build the wamr-rust-sdk crate:
```
cargo build
```

Preparing a Development and Building Environment

For non-espidf targets

Prepare the Rust toolchain
If targeting a non-linux platform, set WAMR_BUILD_TARGET and WAMR_BUILD_PLATFORM in the .cargo/config.toml:
```
[env]
WAMR_BUILD_PLATFORM = "OS name"
WAMR_BUILD_TARGET = "CPU architecture"
```
If targeting a platform not supplied by WAMR, refer to the WAMR porting guide and set WAMR_BUILD_TARGET, WAMR_BUILD_PLATFORM and WAMR_SHARED_PLATFORM_CONFIG in the .cargo/config.toml properly.

For espidf targets

Get the latest information from The Rust on ESP Book.
Please make sure you have installed all prerequisites first!
Generate projects from templates following the instructions in The Rust on ESP Book.
```
$ cargo generate esp-rs/esp-idf-template cargo
# follow prompts from the command
```

Add the following configuration to your project's Cargo.toml:

wamr-rust-sdk = { git = "https://github.com/bytecodealliance/wamr-rust-sdk", features = ["esp-idf"] }

BKMs

Rust on ESP-IDF "Hello, World" template is a good example
Ensure that LIBCLANG_PATH is correctly set (something like: /home//.rustup/toolchains/esp/xtensa-esp32-elf-clang/esp-/esp-clang/lib, if on a Mac). If not, there might be something wrong with your espup installation.

License

joe-p/wamr-rust-sdk

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