os_build/build.rs

use std::{
    os::unix::ffi::OsStrExt,
    path::{Path, PathBuf},
    process::Command,
};

extern crate bootloader;

use bootloader::{BiosBoot, UefiBoot};

fn main() {
    println!("cargo:rerun-if-changed=sysroot");
    println!("cargo:rerun-if-changed=build.rs");

    // set by cargo, build scripts should use this directory for output files
    let out_dir = std::env::var_os("OUT_DIR").unwrap();

    let mut initrd_path = out_dir.clone();
    initrd_path.push("/initrd.tar");
    Command::new("sh")
        .arg("-c")
        .arg(format!("cd sysroot; tar cvf {:?} *", initrd_path))
        .spawn()
        .unwrap()
        .wait()
        .unwrap();

    // set by cargo's artifact dependency feature, see
    // https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#artifact-dependencies
    let kernel = PathBuf::from(std::env::var_os("CARGO_BIN_FILE_KERNEL_kernel").unwrap());

    // create an UEFI disk image (optional)
    let mut uefi_path = out_dir.clone();
    uefi_path.push("/uefi.img");
    UefiBoot::new(&kernel)
        .set_ramdisk(Path::new(&initrd_path))
        .create_disk_image(Path::new(&uefi_path))
        .unwrap();

    // create a BIOS disk image (optional)
    let mut bios_path = out_dir.clone();
    bios_path.push("/bios.img");
    BiosBoot::new(&kernel)
        .set_ramdisk(Path::new(&initrd_path))
        .create_disk_image(Path::new(&bios_path))
        .unwrap();

    println!("cargo:rustc-env=UEFI_PATH={}", uefi_path.to_string_lossy());
    println!("cargo:rustc-env=BIOS_PATH={}", bios_path.to_string_lossy());

    std::fs::write("kernel_path", kernel.as_os_str().as_bytes()).unwrap();
    std::fs::write("initrd_path", initrd_path.as_os_str().as_bytes()).unwrap();
    std::fs::write("out_dir_path", out_dir.as_bytes()).unwrap();
}