use std::env;
use std::fs;
use std::path::Path;
use std::process::Command;
fn main() {
let hash = read_hash_file()
.or_else(git_short)
.unwrap_or_else(|| "unknown".into());
println!("cargo:rustc-env=GIT_HASH={hash}");
println!("cargo:rerun-if-changed=GIT_HASH");
println!("cargo:rerun-if-changed=.git/HEAD");
}
fn read_hash_file() -> Option<String> {
let path = Path::new(&env::var("CARGO_MANIFEST_DIR").ok()?).join("GIT_HASH");
fs::read_to_string(path)
.ok()
.map(|s| s.trim().to_string())
.filter(|s| !s.is_empty())
}
fn git_short() -> Option<String> {
Command::new("git")
.args(["rev-parse", "--short", "HEAD"])
.output()
.ok()
.and_then(|o| String::from_utf8(o.stdout).ok())
.map(|s| s.trim().to_string())
}