fn bindgen()

in build.rs [37:89]
35 lines of code
4 McCabe index (conditional complexity)

fn bindgen() {
    let target_os = env::var("CARGO_CFG_TARGET_OS").expect("CARGO_CFG_TARGET_OS was not set");

    // Platforms currently not supported.
    //
    // See <https://github.com/mozilla/mtu/issues/82>.
    if matches!(target_os.as_str(), "ios" | "tvos" | "visionos") {
        return;
    }

    if target_os == "windows" {
        return;
    }

    let bindings = if matches!(target_os.as_str(), "linux" | "android") {
        bindgen::Builder::default()
            .header_contents("rtnetlink.h", "#include <linux/rtnetlink.h>")
            // Only generate bindings for the following types
            .allowlist_type("rtattr|rtmsg|ifinfomsg|nlmsghdr")
    } else {
        bindgen::Builder::default()
        .header_contents(
            "route.h",
            "#include <sys/types.h>\n#include <sys/socket.h>\n#include <net/route.h>\n#include <net/if.h>",
        )
        // Only generate bindings for the following types and items
        .allowlist_type("rt_msghdr|rt_metrics|if_data")
        .allowlist_item("RTAX_MAX|RTM_GET|RTM_VERSION|RTA_DST|RTA_IFP")
    };

    let bindings = bindings
        .clang_args(clang_args())
        // Tell cargo to invalidate the built crate whenever any of the
        // included header files changed.
        .parse_callbacks(Box::new(bindgen::CargoCallbacks::new()))
        // Constants should be generated as &CStr instead of &[u8].
        .generate_cstr(true)
        // Always emit explicit padding fields.
        .explicit_padding(true)
        // Default trait should be derived when possible
        .derive_default(true)
        // Finish the builder and generate the bindings.
        .generate()
        // Unwrap the Result and panic on failure.
        .expect("Unable to generate bindings");

    // Write the bindings to the $OUT_DIR/$BINDINGS file.
    let out_path = std::path::PathBuf::from(env::var("OUT_DIR").unwrap()).join(BINDINGS);
    bindings
        .write_to_file(out_path.clone())
        .expect("Couldn't write bindings!");
    println!("cargo:rustc-env=BINDINGS={}", out_path.display());
}