Show git short sha on splash screen

firmware/Cargo.toml

@@ -34,6 +34,9 @@ lto = "fat"
 opt-level = "s"
 overflow-checks = false
 
+[build-dependencies]
+git2 = "0.19"
+
 [dependencies]
 display-interface = "0.5"
 embassy-executor = { version = "0.5", features = ["log"] }

firmware/build.rs

@@ -0,0 +1,24 @@
+use core::str;
+use git2::{Repository, StatusOptions};
+use std::{env, error::Error};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    // In contrast to git describe, we don't want to show a tag name, but always the short sha and
+    // dirty status as a useful addition to the version number in CARGO_PKG_VERSION.
+    let repo = Repository::discover(env::var("CARGO_MANIFEST_DIR")?)?;
+    let head_obj = repo.revparse_single("HEAD")?;
+    let short_sha_buf = head_obj.short_id()?;
+    let short_sha = str::from_utf8(&short_sha_buf)?;
+    let mut status_options = StatusOptions::default();
+    // let _ = status_options.include_untracked(true);
+    let statuses = repo.statuses(Some(&mut status_options))?;
+    let dirty = statuses.iter().any(|st| !st.status().is_ignored());
+    let dirty_str = if dirty { "+" } else { "" };
+    println!("cargo::rustc-env=GIT_SHORT_SHA={}{}", short_sha, dirty_str);
+
+    println!("cargo::rerun-if-changed=build.rs");
+    println!("cargo::rerun-if-changed=.git/");
+    println!("cargo::rerun-if-changed=.git/HEAD");
+
+    Ok(())
+}

firmware/src/display.rs

@@ -1,4 +1,4 @@
-use embedded_graphics::mono_font::ascii::{FONT_10X20, FONT_6X10, FONT_9X18_BOLD};
+use embedded_graphics::mono_font::ascii::{FONT_10X20, FONT_5X8, FONT_6X10, FONT_9X18_BOLD};
 use embedded_graphics::mono_font::MonoTextStyle;
 use embedded_graphics::pixelcolor::BinaryColor;
 use embedded_graphics::prelude::*;
@@ -65,6 +65,13 @@ impl<I2C: I2c> Display<I2C> {
             Alignment::Center,
         )
         .draw(&mut self.driver)?;
+        Text::with_alignment(
+            env!("GIT_SHORT_SHA"),
+            Point::new(127, 63),
+            MonoTextStyle::new(&FONT_5X8, BinaryColor::On),
+            Alignment::Right,
+        )
+        .draw(&mut self.driver)?;
         self.driver.flush()?;
         Ok(())
     }