build.rs

use std::env;
use std::fs::File;
use std::io::Write;
use std::path::{Path, PathBuf};
use std::process::Command;

// Copied from https://blog.biofan.org/2019/08/cargo-build-script/
fn get_git_version() -> String {
    let version = env::var("CARGO_PKG_VERSION").unwrap();

    let child = Command::new("git").args(["describe", "--always"]).output();
    match child {
        Ok(child) => {
            let buf = String::from_utf8(child.stdout).expect("failed to read stdout");
            version + "-" + &buf
        }
        Err(err) => {
            eprintln!("`git describe` err: {}", err);
            version
        }
    }
}

fn build_yak() {
    let c_dir = PathBuf::from("./yak");
    let mut has_yak = false;
    if let Ok(iter_files) = c_dir.read_dir(){
        for file in iter_files.flatten(){
            let fpath = file.path();
            if fpath
                .extension()
                .map_or_else(|| true, |x| x != "o" && x != "a")
            {
                println!("cargo:rerun-if-changed={:?}", fpath);
            }
            if !has_yak{
                has_yak = true;
            }
        }
    }

    if has_yak {
        let output = Command::new("make")
            .arg("all")
            .current_dir(&c_dir)
            .output()
            .expect("failed to execute process");
        if !output.status.success() {
            panic!("make error: {}", String::from_utf8_lossy(&output.stderr));
        }
    }
}

fn main() {
    build_yak();
    let version = get_git_version();
    let mut f = File::create(Path::new(&env::var("OUT_DIR").unwrap()).join("VERSION")).unwrap();
    f.write_all(version.trim().as_bytes()).unwrap();
}