npro on sai

.sai.json uses the C tree's platform names, so a builder that already serves libwebsockets serves npro too once it has a Rust toolchain. This is what each one needs, and what each configuration checks.

How the config is shaped

sai's step template substitutes three variables, ${prep}, ${cmake} and ${cpack}, so the name cmake is sai's and not a build system's. Every unix platform has one step, scripts/sai.sh ${cmake}. Each configuration's cmake names a profile in that script:

How the C build's dimensions map here: - The cmake option dimensions become the features configuration. cargo-hack builds every combination of features, so no configuration per combination is written. - Platforms stay platforms. - Machines sai has no builder for, big-endian and 32-bit, are interpreted by Miri rather than run on hardware.

Installing Rust on a builder

Install as the user the sai builder runs jobs as. sai sets HOME to the builder's home for each job, and scripts/sai.sh puts $HOME/.cargo/bin first on PATH, so rustup's usual per-user install is found without changing the builder daemon's environment.

Every unix builder with rustup

These are the Linux builders (x86_64, aarch64 and riscv64) and the macOS ones. rustup provides host toolchains for all of them. A C linker must be present: it is already, as these builders build C lws. On macOS that means the Xcode command line tools.

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile default

That gives stable with rustfmt and clippy, which is all the test profile needs. Updating later is rustup update.

A distro's packaged cargo is usually too old: Ubuntu noble's is 1.75, and npro needs the workspace's rust-version, 1.85, the first to know edition 2024. scripts/sai.sh checks rustc before anything else, and refuses an older one with the install command, rather than leaving cargo to fail parsing the manifest.

The fedora44 x86_64 builder, which runs everything else

On top of the above:

rustup toolchain install 1.85 --profile minimal          # the MSRV build
rustup toolchain install nightly --profile minimal --component miri,rust-src
rustup target add thumbv6m-none-eabi thumbv7em-none-eabihf riscv32imc-unknown-none-elf
cargo install --locked cargo-deny cargo-audit cargo-hack
dnf install cmake gcc zlib-devel git                   # the C oracle build

The first Miri run of each target builds that target's standard library for Miri, and takes a few minutes. Later runs reuse it.

Network access during jobs: - cargo audit fetches the RustSec advisory database from github.com on each run; - the oracle clones and fetches libwebsockets from libwebsockets.org, keeping its checkout in $HOME/lws-oracle (or $LWS_ORACLE).

Nothing else fetches. The workspace has no dependencies, and every build is --locked.

freebsd/aarch64

rustup has no host toolchain for aarch64 FreeBSD, so use the packaged one, which must be at least the workspace's rust-version (1.85):

pkg install rust

It installs under /usr/local/bin, which the builder's PATH already has.

w11/x86_64 (MSVC)

Run rustup-init.exe from <https://rustup.rs> with the default host, x86_64-pc-windows-msvc; the builder already has the Visual Studio build tools it links with. Do it as the account the sai builder service runs as, and make sure that account's %USERPROFILE%\.cargo\bin is on the service's PATH, since the Windows step runs cargo directly under cmd.

Later

• esp32: building for the ESP32's xtensa cores needs Espressif's Rust fork, installed with espup. That waits until there is something to run on the device.
• fuzzing: cargo-fuzz needs nightly and clang. It joins the fuzz builder once the h1 parser has fuzz targets.

A possible sai change

Nothing here needs sai changed. A neutral name for the configuration key, such as build beside cmake, would make npro's .sai.json read better, but cmake does the job as it is.