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fuchsia / fuchsia / main / . / src / lib / diagnostics / log / message / rust / cpp-log-decoder
tree: 4ef051a7f71bddda7c3926dff0a3103d67a8c595 [path history] [tgz]
  1. src/
  2. BUILD.gn
  3. cbindgen.toml
  4. log_decoder.h
  5. log_decoder_api.h
  6. README.md
  7. test.cc
src/lib/diagnostics/log/message/rust/cpp-log-decoder/README.md

cpp-log-decoder

Static FFI library that provides an entry point to the Rust log decoder.

How to update FFI bindings

The cbindgen program reads a locally generated Cargo.toml manifest to create the header for the cpp-log-decoder static Rust library, and its dependencies, to expose a public C API.

There are four steps to create/update the bindings header:

  1. Link the Fuchsia (or nightly) Rust toolchain.
  2. Install cbindgen.
  3. Generate the local Cargo.toml manifest.
  4. Create/update the bindings headers.
  5. Format the header.

Link the Fuchsia Rust (or nightly) toolchain

The stable Rust toolchain cannot process Fuchsia-generated Cargo.toml manifests. You therefore must link the Fuchsia toolchain in your environment:

rustup toolchain link fuchsia "~/fuchsia/prebuilt/third_party/rust/linux-x64"

If you cannot link this toolchain in your environment, you may alternately use the nightly Rust toolchain instead.

Install cbindgen

We currently pin cbindgen at version 0.26.0 to avoid unexpected behavior with cbindgen updates. You can install it with the following:

cargo install --version 0.26.0 --force cbindgen

Generate the local Cargo.toml manifest for cpp-log-decoder

Generate a Cargo.toml by following the instructions on fuchsia.dev for the build target //src/lib/diagnostics/log/message/rust/cpp-log-decoder:staticlib.

As of this writing, this is done in the following way.

  1. Using fx args, add //build/rust:cargo_toml_gen to host_labels.

  2. Using fx args, add //src/lib/diagnostics/log/message/rust/cpp-log-decoder:staticlib to build_only_labels.

  3. Build the cargo_toml_gen target and generate the Cargo.toml manifest:

fx args # then append "//build/rust:cargo_toml_gen" to `host_labels`
fx args # then append "//src/diagnostics/lib/cpp-log-decoder:staticlib"
        # to `build_only_labels`

fx build //build/rust:cargo_toml_gen
fx gen-cargo //src/lib/diagnostics/log/message/rust/cpp-log-decoder:_log_decoder_c_bindings_rustc_static.actual
fx gen-cargo //src/lib/diagnostics/log/message/rust:lib.actual

Create/update the bindings header

The following command uses the Fuchsia toolchain and cbindgen to create/update the bindings header. If you could not link the Fuchsia toolchain, you may substitute RUSTUP_TOOLCHAIN=nightly.

RUSTUP_TOOLCHAIN=fuchsia cbindgen ~/fuchsia/src/lib/diagnostics/log/message/rust/cpp-log-decoder -o ~/fuchsia/src/lib/diagnostics/log/message/rust/cpp-log-decoder/log_decoder.h