88 lines
4.0 KiB
Markdown
88 lines
4.0 KiB
Markdown
libcsp-rust
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=========
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This project aims to provide libraries and tools to use
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[`libcsp`](https://github.com/libcsp/libcsp) in your Rust project.
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It provides 2 crates for this:
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- [`libcsp-cargo-build`](https://egit.irs.uni-stuttgart.de/rust/libcsp-rust/src/branch/main/libcsp-cargo-build)
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provides an API to build the `libcsp` using `cargo` with the [`cc`](https://docs.rs/cc/latest/cc/) crate.
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- [`libcsp-rust`](https://egit.irs.uni-stuttgart.de/rust/libcsp-rust/src/branch/main/libcsp-rust)
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provides the Rust bindings to `libcsp` and a safe and ergonomic Rust interface.
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In addition, it provides a workspace to allow updating the `libcsp` and the corresponding bindings
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more easily inside the `lib` directory. Some of the examples `libcsp` provides were ported to Rust
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and are showcases in the `examples` directory.
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## How it works
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We assume that cargo should also take care of building the library.
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1. Add the `libcsp-cargo-build` as a build dependency inside your `Cargo.toml`.
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2. Add the `libcsp-rust` as a regular dependency inside your `Cargo.toml`.
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3. Create a custom `build.rs` script which takes care of building `libcsp` using the API
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provided by `libcsp-cargo-build`. You have to provide the source code for `libcsp` inside some
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directory and pass the directory path to a builder API.
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4. You can now write regular Rust code and use the API provided by `libcsp-rust` to use `libcsp`
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in a safe and Rusty way.
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It is recommended to have a look at the [example build script](https://egit.irs.uni-stuttgart.de/rust/libcsp-rust/src/branch/main/examples/build.rs)
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which should give you a general idea of how a build script might look like to integrate `libcsp`.
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## Running the example
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The example uses both the builder crate and the bindings and API crate and implements the
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[server/client example](https://github.com/libcsp/libcsp/blob/develop/examples/csp_server_client.c)
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in Rust. You can run the example using the following steps:
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1. Clone `libcsp` into the `lib` folder, for example by using the provided `lib/clone-csp.sh`
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script.
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2. You can now use `cargo run -p libcsp-rust-examples` to run the server/client example.
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## Compile-time configuration of the `libcsp-rust` library
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The `libcsp-rust` library requires some compile-time configuration file to be included to work
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properly. You can see an example version of the file for the workspace
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[here](https://egit.irs.uni-stuttgart.de/rust/libcsp-rust/src/branch/main/examples/autoconfig.rs).
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The user has to provide the path to a directory containing this `autoconfig.rs` file using the
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`CSP_CONFIG_DIR` environmental variable.
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You can automatically generate this file when using `libcsp-cargo-build` by using the
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[`generate_autoconf_rust_file`] method of the Builder object as done in the example build script.
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In this workspace, the `CSP_CONFIG_DIR` variable is hardcoded using the following `.cargo/config.toml`
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configuration:
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```toml
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[env]
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CSP_CONFIG_DIR = { value = "examples", relative = true }
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```
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## Generating and update the bindings using the `lib` folder
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The `lib` folder in this repository serves as the staging directory for the `libcsp` library to
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build. However, it can also be used to update the bindings provided in `libcsp-rust` by providing
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some tools and helpers to auto-generate and update the bindings file `bindings.rs`.
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If you want to do this, you should install `bindgen-cli` first:
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```sh
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cargo install bindgen-cli --locked
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```
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`bindgen` needs some additional information provided by the user to generate the bindings:
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An `autoconfig.h` file which is used to configure `libcsp`. Normally, this file is generated
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by the C build system. This file is located at `cfg/csp` and is also updated automatically
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when running the example application.
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After cloning the repository, you can now run the following command to re-generate the bindings
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file:
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```sh
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bindgen --use-core wrapper.h -- "-I./libcsp/include" "-I./cfg" "-I./libcsp/src" > bindings.rs
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```
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With the bindings file, you can now manually update the FFI bindings provided in
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`libcsp-rust/src/ffi.rs` or in your own CSP library.
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