build.rs

#![warn(
    clippy::cargo,
    clippy::missing_docs_in_private_items,
    clippy::nursery,
    clippy::pedantic,
    missing_docs
)]

//!
//! - Re-export path to the crashpad handler to the crate, only used during
//!   testing.
//! - Copies `crashpad_handler(.exe)` to the default binary output directory.

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

fn main() {
    if let Ok(handler) = env::var("DEP_SENTRY_NATIVE_CRASHPAD_HANDLER") {
        println!("cargo:rustc-cfg=crashpad");
        println!("cargo:rustc-env=CRASHPAD_HANDLER={}", handler);

        let out_dir: PathBuf = env::var_os("OUT_DIR").expect("out dir not set").into();

        // OUT_DIR will point to a directory unique to each crate, which be something
        // like target/debug/build/sentry-contrib-native-sys-f734ae671f48a2d5/
        // out, so we go up 3 parents to get to the root directory (target/debug
        // in this case), which is where the final binary artifacts will be
        // placed by cargo, so we copy the crashpad_handler to the same
        // directory to fit with the default expectation the handler is next to
        // the executable it is monitoring, and so that scripts/programs
        // that want to package the crashpad_handler along with the executable don't
        // have to trawl through the target directory looking for it, as,
        // AFAICT, there is no convenient way to specify the output path of the
        // handler where it is available to eg other builds scripts, as noted by
        // cargo
        //
        // > Note that metadata is only passed to immediate dependents, not transitive
        // dependents.
        //
        // And we can't assume that this crate will be a direct dependency of the crate.
        let bin_dir = out_dir
            .parent()
            .and_then(Path::parent)
            .and_then(Path::parent)
            .expect("failed to find default binary output path");

        let handler = PathBuf::from(handler);
        let bin_path = bin_dir.join(
            handler
                .file_name()
                .expect("handler doesn't have a file name"),
        );

        // Make sure we re-copy the file to the desired output directory if it
        // gets deleted.
        println!("cargo:rerun-if-changed={}", bin_path.display());
        fs::copy(&handler, &bin_path).expect("failed to copy sentry crash handler");
    }
}