build.rs

// Copyright 2023 LiveKit, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::{
    env,
    path::{Path, PathBuf},
};

const PROTO_SRC_DIR: &str = "protocol";

fn main() {
    if env::var("DOCS_RS").is_ok() {
        return;
    }
    download_webrtc();
    copy_webrtc_license();
    configure_linker();
    get_lib_path();
    generate_protobuf();
}

fn download_webrtc() {
    let webrtc_dir = webrtc_sys_build::webrtc_dir();
    if !webrtc_dir.exists() {
        webrtc_sys_build::download_webrtc().unwrap();
    }
}

/// Copy the webrtc license to `CARGO_MANIFEST_DIR`, used by the FFI release action.
fn copy_webrtc_license() {
    let webrtc_dir = webrtc_sys_build::webrtc_dir();
    let license = webrtc_dir.join("LICENSE.md");
    let target_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
    let out_file = Path::new(&target_dir).join("WEBRTC_LICENSE.md");
    std::fs::copy(license, out_file).unwrap();
}

fn configure_linker() {
    let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
    match target_os.as_str() {
        "windows" => {}
        "linux" => {
            println!("cargo:rustc-link-lib=static=webrtc");
        }
        "android" => {
            webrtc_sys_build::configure_jni_symbols().unwrap();
        }
        "macos" | "ios" => {
            println!("cargo:rustc-link-arg=-ObjC");
        }
        _ => {
            panic!("Unsupported target, {}", target_os);
        }
    }
}

/// Get the path of the built library in the target directory, used for integration testing.
fn get_lib_path() {
    let out_dir = PathBuf::from(std::env::var("OUT_DIR").unwrap());
    let target_dir = out_dir.ancestors().nth(4).expect("Failed to find target directory");

    let build_profile = env::var("PROFILE").unwrap();
    let output_dir = target_dir.join(build_profile);

    let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
    let lib_extension = match target_os.as_str() {
        "windows" => "dll",
        "linux" | "android" => "so",
        "macos" => "dylib",
        "ios" => "a",
        _ => {
            panic!("Unsupported target, {}", target_os);
        }
    };
    let crate_name = env::var("CARGO_PKG_NAME").unwrap();
    let lib_name = format!("lib{}.{}", crate_name.replace("-", "_"), lib_extension);
    let lib_path = output_dir.join(lib_name);
    println!("cargo::rustc-env=FFI_LIB_PATH={}", lib_path.display());
}

fn generate_protobuf() {
    let paths: Vec<_> = std::fs::read_dir(PROTO_SRC_DIR)
        .expect("Failed to read protobuf source directory")
        .map(|entry| entry.unwrap().path())
        .filter(|path| path.extension().is_some_and(|ext| ext == "proto"))
        .collect();
    for path in &paths {
        println!("cargo:rerun-if-changed={}", path.display());
    }
    prost_build::Config::new()
        .compile_protos(&paths, &[PROTO_SRC_DIR])
        .expect("Protobuf generation failed");
}