bt-affordances

The bt-affordances are a Rust library with C FFI bindings that expose basic Bluetooth workflows for automated testing and tooling.

How to update the C FFI bindings to the Rust affordances

The bindings are generated using cbindgen. The Rust library is contained in src/rust_affordances. The bindings are located at ffi_c/bindings.h.

To (re)generate these bindings,

1. Link the Rust toolchain in your environment (details on fuchsia.dev):

$ rustup toolchain link fuchsia $($FUCHSIA_DIR/scripts/youcompleteme/paths.py VSCODE_RUST_TOOLCHAIN)
$ rustup default fuchsia

2. Install cbindgen. The latest version with which we've validated compatibility is 0.28.0:

$ cargo install --version 0.28.0 --force cbindgen

3. Generate a Cargo.toml manifest for the Rust library (details on fuchsia.dev):

fx args # then append "//build/rust:cargo_toml_gen" to `host_labels`
fx args # then append "//src/connectivity/bluetooth/testing/bt-affordances:_affordances_c_rustc_static"
        # to `build_only_labels`

fx build //build/rust:cargo_toml_gen
fx gen-cargo //src/connectivity/bluetooth/testing/bt-affordances:_affordances_c_rustc_static

4. Create/update the bindings.h header. It's normal to see some warnings when running this command:

RUSTUP_TOOLCHAIN=fuchsia cbindgen $FUCHSIA_DIR/src/connectivity/bluetooth/testing/bt-affordances/ -o $FUCHSIA_DIR/src/connectivity/bluetooth/testing/bt-affordances/ffi_c/bindings.h

5. Add Fuchsia copyright and header guards to bindings.h:

// Copyright 2025 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SRC_CONNECTIVITY_BLUETOOTH_TESTING_BT_AFFORDANCES_FFI_C_BINDINGS_H_
#define SRC_CONNECTIVITY_BLUETOOTH_TESTING_BT_AFFORDANCES_FFI_C_BINDINGS_H_

... (don't modify the autogenerated code) ...

#endif  // SRC_CONNECTIVITY_BLUETOOTH_TESTING_BT_AFFORDANCES_FFI_C_BINDINGS_H_

This enables you to run fx format-code to format bindings.h.