Indicate when file has changed on disk

src/util.rs

@@ -1,6 +1,8 @@
-use std::sync::mpsc;
+use std::{fs::File, os::unix::fs::MetadataExt as _, sync::mpsc};
 
+use chrono::{DateTime, Local};
 use egui::Id;
+use eyre::{Context, ContextCompat};
 use rand::{Rng, rng};
 
 pub fn random_id() -> Id {
@@ -28,3 +30,27 @@ impl<T> GuiSender<T> {
         Ok(())
     }
 }
+
+#[track_caller]
+pub fn log_error<T>(chain: eyre::Report, f: impl FnOnce() -> eyre::Result<T>) -> Option<T> {
+    f().map_err(|e| e.wrap_err(chain))
+        .inspect_err(|e| log::error!("{e}"))
+        .ok()
+}
+
+pub fn file_mtime(file: &File) -> eyre::Result<DateTime<Local>> {
+    (move || {
+        let meta = file.metadata().wrap_err("Failed to stat file")?;
+
+        let sec = meta.mtime();
+        let nsec = meta
+            .mtime_nsec()
+            .try_into()
+            .wrap_err("Nanoseconds overflowed")?;
+
+        DateTime::from_timestamp(sec, nsec)
+            .wrap_err("Bad timestamp")
+            .map(Into::into)
+    })()
+    .wrap_err("Failed to get file mtime")
+}