firmware: add commit hash into firmware

build.rs

@@ -1,4 +1,4 @@
-use std::{env, fs::File, io::Write, path::PathBuf};
+use std::{env, fs::File, io::Write, path::PathBuf, process::Command};
 
 fn main() {
     // Put the linker script somewhere the linker can find it
@@ -12,4 +12,34 @@ fn main() {
     // Only re-run the build script when memory.x is changed,
     // instead of when any part of the source code changes.
     println!("cargo:rerun-if-changed=memory.x");
+
+    let revision = env::var("BUILD_REVISION");
+    match revision {
+        Ok(r) => {
+            // Skip if the environment variable is already set
+            println!("cargo:rustc-env=BUILD_REVISION={}", r);
+        }
+        Err(_) => {
+            let output = Command::new("git")
+                .args(&["rev-parse", "--short=7", "HEAD"])
+                .output()
+                .expect("Failed to execute git command");
+            
+            let dirty = !Command::new("git")
+                .args(&["status", "-s"])
+                .output()
+                .expect("Failed to execute git command").stdout.is_empty();
+            
+            let build_revision: String;
+            if dirty {
+                build_revision = String::from_utf8(output.stdout)
+                    .expect("Invalid UTF-8 sequence") + "-dirty";
+            } else {
+                build_revision = String::from_utf8(output.stdout)
+                    .expect("Invalid UTF-8 sequence");
+            }
+            
+            println!("cargo:rustc-env=BUILD_REVISION={}", build_revision.trim());
+        }
+    };
 }

flake.nix

@@ -39,6 +39,7 @@
         nativeBuildInputs = [ pkgs.llvm ];
 
         buildPhase = ''
+          export BUILD_REVISION=${toString (self.shortRev or self.dirtyShortRev or "unknown")}
           cargo build --release --bin kirdy
         '';