build.rs

extern crate cbindgen;

use cbindgen::{Config, Language};
use std::env;
use std::path::{Path, PathBuf};

fn get_target_dir(manifest_dir: &str) -> PathBuf {
    if let Ok(target) = env::var("CARGO_TARGET_DIR") {
        // allow a CARGO_TARGET_DIR var that could be set via e.g. cmake to override where we put
        // the header files
        PathBuf::from(target)
    } else {
        let mut manifest_dir = PathBuf::from(manifest_dir);
        manifest_dir.pop(); // go up, since we're a sub-crate
        manifest_dir.join("target").join("ffi-headers")
    }
}

fn main() {
    let crate_dir = env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR should be set");
    let package_name = env::var("CARGO_PKG_NAME").expect("CARGO_PKG_NAME should be set");
    let target_dir = get_target_dir(crate_dir.as_str());
    let cbindgen_toml = Path::new(&crate_dir).join("cbindgen.toml");
    let mut config = Config::from_file(&cbindgen_toml)
        .unwrap_or_else(|_| panic!("Couldn't find {}", cbindgen_toml.display()));

    // generate cxx bindings
    let output_file_hpp = target_dir
        .join(format!("{}.hpp", package_name))
        .display()
        .to_string();
    let mut config_hpp = config.clone();
    config_hpp.language = Language::Cxx;
    cbindgen::generate_with_config(&crate_dir, config_hpp)
        .expect("generate_with_config should have worked for Cxx")
        .write_to_file(output_file_hpp);

    // generate c bindings
    let output_file_h = target_dir
        .join(format!("{}.h", package_name))
        .display()
        .to_string();
    config.language = Language::C;
    cbindgen::generate_with_config(&crate_dir, config)
        .expect("generate_with_config should have worked for C")
        .write_to_file(output_file_h);
}