WIP ble: Add device information service

TODO: Determine "git describe" size

build.rs

@@ -17,6 +17,21 @@ fn main() -> std::io::Result<()> {
         .compile_well_known_types()
         .compile_protos(&["docs/c_its-messages.proto"], &["docs/"])?;
 
+    // get git revision
+    println!("cargo:rustc-rerun-if-changed=.git/HEAD");
+
+    println!(
+        "cargo:rustc-env=GIT_REVISION={}",
+        String::from_utf8(
+            std::process::Command::new("git")
+                .args(&["describe", "--always"])
+                .output()
+                .unwrap()
+                .stdout,
+        )
+        .unwrap()
+    );
+
     Ok(())
 }