Initial commit

breadmill/src/power.rs

@@ -0,0 +1,31 @@
+use std::fs;
+use std::path::Path;
+
+/// Best-effort check for whether the system is currently on AC/mains power.
+/// Scans `/sys/class/power_supply` for a Mains or USB supply with `online=1`.
+/// Systems with no such supply at all (desktops, no battery) are treated as
+/// always on power, so this never blocks indexing on hardware without a
+/// battery to protect.
+pub fn on_ac_power() -> bool {
+    let dir = Path::new("/sys/class/power_supply");
+    let Ok(entries) = fs::read_dir(dir) else {
+        return true;
+    };
+
+    let mut found_mains = false;
+    for entry in entries.flatten() {
+        let path = entry.path();
+        let supply_type = fs::read_to_string(path.join("type")).unwrap_or_default();
+        let supply_type = supply_type.trim();
+        if supply_type != "Mains" && supply_type != "USB" {
+            continue;
+        }
+        found_mains = true;
+        let online = fs::read_to_string(path.join("online")).unwrap_or_default();
+        if online.trim() == "1" {
+            return true;
+        }
+    }
+
+    !found_mains
+}