core/server/build.rs

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

use std::path::PathBuf;
use std::{env, error};
use vergen_git2::{Build, Cargo, Emitter, Git2, Rustc, Sysinfo};

const WEB_ASSETS_PATH: &str = "web/build/static";
const WEB_INDEX_FILE: &str = "web/build/static/index.html";

fn main() -> Result<(), Box<dyn error::Error>> {
    stub_libm_for_musl();
    verify_web_assets_if_enabled();
    emit_vergen_instructions()?;
    Ok(())
}

// Vendored `hwloc` references `cbrt`, which makes the linker pull in a
// `libm`. musl folds the math functions into its `libc`, so the Rust
// musl sysroot ships no `libm.a`. Without one, `-lm` falls through to
// the host glibc's `libm.a`, whose `cbrt` needs glibc-internal
// `__frexp`/`__ldexp` symbols that do not exist on musl, and the static
// link fails. Drop an empty `libm.a` stub on the search path so `-lm`
// resolves to nothing and `cbrt` is satisfied later by musl's own
// `libc`. No effect on non-musl targets.
fn stub_libm_for_musl() {
    if env::var("CARGO_CFG_TARGET_ENV").as_deref() != Ok("musl") {
        return;
    }

    let out_dir = env::var("OUT_DIR").expect("OUT_DIR is set by cargo for build scripts");
    let stub = PathBuf::from(&out_dir).join("libm.a");

    // `!<arch>\n` is the canonical header of an empty `ar` archive.
    std::fs::write(&stub, b"!<arch>\n").expect("write empty libm.a stub");

    println!("cargo:rustc-link-search=native={out_dir}");
}

/// Returns the workspace root (iggy/), two levels up from core/server.
fn workspace_root() -> PathBuf {
    PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap())
        .parent()
        .and_then(|p| p.parent())
        .expect("server crate must be at core/server within workspace")
        .to_path_buf()
}

fn emit_vergen_instructions() -> Result<(), Box<dyn error::Error>> {
    if option_env!("IGGY_CI_BUILD") != Some("true") {
        println!("cargo:info=Skipping vergen because IGGY_CI_BUILD is not set to 'true'");
        return Ok(());
    }

    Emitter::default()
        .add_instructions(&Build::all_build())?
        .add_instructions(&Cargo::all_cargo())?
        .add_instructions(&Git2::all_git())?
        .add_instructions(&Rustc::all_rustc())?
        .add_instructions(&Sysinfo::all_sysinfo())?
        .emit()?;

    let configs_path = workspace_root()
        .join("core/configs")
        .canonicalize()
        .unwrap_or_else(|e| panic!("Failed to canonicalize configs path: {e}"));

    println!("cargo:rerun-if-changed={}", configs_path.display());
    Ok(())
}

fn verify_web_assets_if_enabled() {
    if env::var("CARGO_FEATURE_IGGY_WEB").is_err() {
        return;
    }

    let assets_dir = workspace_root().join(WEB_ASSETS_PATH);
    let index_file = workspace_root().join(WEB_INDEX_FILE);

    println!("cargo:rerun-if-changed={}", assets_dir.display());

    if !assets_dir.exists() || !index_file.exists() {
        println!(
            "cargo:info=Web UI assets not found at {}. \
             To build them, run: npm --prefix web ci && npm --prefix web run build:static",
            assets_dir.display()
        );
        return;
    }

    println!(
        "cargo:info=Web UI assets verified at {}",
        assets_dir.display()
    );
}