generate build metadata

build.rs

@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2021  Aravinth Manivannan <realaravinth@batsense.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+use std::process::Command;
+
+fn main() {
+    let output = Command::new("git")
+        .args(&["rev-parse", "HEAD"])
+        .output()
+        .expect("error in git command, is git installed?");
+    let git_hash = String::from_utf8(output.stdout).unwrap();
+    println!("cargo:rustc-env=GIT_HASH={}", git_hash);
+}