build.rs

The build.rs file’s main function is a build script that configures the Rust compiler to link against the dynamic library by telling cargo through standard output (print).

dynamic library path: cargo:rustc-link-search=native=$PATH

dynamic library name: cargo:rustc-link-lib=dylib=$NAME

Bindgen

library path

wrapper header path

output binding rust file


    let bindings = bindgen::Builder::default()
        // The input header we would like to generate
        // bindings for.
        .header("wrapper.h")
        .clang_arg("-v")
        .derive_debug(true)
        .derive_default(true)
        // included header files changed.
        .parse_callbacks(Box::new(bindgen::CargoCallbacks::new()))
        // 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.rs file.
    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
    bindings
        .write_to_file(out_path.join("bindings.rs"))
        .expect("Couldn't write bindings!");

build.rs binding in lib.rs

lib.rs file can include the generated bindings and allows the Rust code to interact with the C functions.

The #![allow(...)] attributes are used to suppress warnings about naming conventions.

include!(concat!(env!("OUT_DIR"), "/bindings.rs"));: This line includes the generated bindings file, which is created by bindgen during the build process.

Source code usage

The extern "C" block declares the image_classifier function from the Darknet library, making it available for use in Rust.

This function can be called from the Rust code as if it were a normal Rust function.

build.rs

Bindgen

build.rs binding in lib.rs

Source code usage

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