van-leds fix round 1: realistic sysfs fake, error paths, stale failover state, log-once, interval and empty-iface guards

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KqhjP7nud5gdBg25zCiRk9

leds/van-leds

@@ -23,6 +23,8 @@ import os
 import signal
 import sys
 import threading
+import time
+from datetime import datetime
 
 DEFAULTS = {
     "led_power": "", "led_lan": "", "led_wan": "", "led_wlan": "",
@@ -31,6 +33,7 @@ DEFAULTS = {
     "sysfs_leds": "/sys/class/leds",
     "sysfs_net": "/sys/class/net",
     "failover_state": "/run/van-failover/state.json",
+    "state_max_age_s": 60,      # older failover state is ignored (wired-uplink fallback)
 }
 LED_KEYS = (("power", "led_power"), ("lan", "led_lan"), ("wan", "led_wan"), ("wlan", "led_wlan"))
 
@@ -41,6 +44,27 @@ def log(msg):
     print(msg, flush=True)
 
 
+_last = {}
+
+
+def log_once(key, msg):
+    """Log msg unless it is what this key last logged (a persistent failure is logged once)."""
+    if _last.get(key) != msg:
+        _last[key] = msg
+        log(msg)
+
+
+def clear_log(key):
+    _last.pop(key, None)
+
+
+def interval(cfg):
+    try:
+        return max(1.0, float(cfg["poll_interval_s"]))
+    except (TypeError, ValueError):
+        return 5.0
+
+
 def load_config(path):
     cfg = dict(DEFAULTS)
     with open(path) as f:
@@ -65,8 +89,19 @@ def write_attr(path, value):
         f.write(str(value))
 
 
-def desired_wan(state, uplink_carrier, uplink=None):
-    """-> ("netdev", device) | ("heartbeat", None) | ("none", None)."""
+def state_stale(state, now, max_age):
+    """True when state["updated"] parses and is older than max_age seconds (unparseable: not stale)."""
+    try:
+        t = datetime.strptime(state["updated"], "%Y-%m-%dT%H:%M:%S%z").timestamp()
+    except (TypeError, KeyError, ValueError):
+        return False
+    return now - t > max_age
+
+
+def desired_wan(state, uplink_carrier, uplink=None, now=None, max_age=60):
+    """-> ("netdev", device) | ("heartbeat", None) | ("none", None). `now`: epoch seconds (default: clock)."""
+    if isinstance(state, dict) and state_stale(state, time.time() if now is None else now, max_age):
+        state = None
     valid = isinstance(state, dict) and isinstance(state.get("wans"), list) and "active_device" in state
     if not valid:  # no failover info: judge by the wired uplink alone
         if not uplink_carrier:
@@ -113,9 +148,10 @@ def carrier(cfg, iface):
     return bool(iface) and read_attr(os.path.join(cfg["sysfs_net"], iface, "carrier")) == "1"
 
 
-def wanted(cfg):
+def wanted(cfg, now=None):
     """{role: (trigger, device)} for every role (before skipping absent LEDs)."""
-    wan = desired_wan(load_state(cfg["failover_state"]), carrier(cfg, cfg["uplink_iface"]), cfg["uplink_iface"] or None)
+    wan = desired_wan(load_state(cfg["failover_state"]), carrier(cfg, cfg["uplink_iface"]),
+                      cfg["uplink_iface"] or None, now, cfg["state_max_age_s"])
     return {
         "power": ("default-on", None),
         "lan": ("netdev", cfg["lan_iface"]),
@@ -133,6 +169,11 @@ def usable_leds(cfg, announce=False):
             if announce:
                 log(f"LED {role}: no name configured, skipped")
             continue
+        iface_key = {"lan": "lan_iface", "wlan": "wlan_iface"}.get(role)
+        if iface_key and not cfg[iface_key]:
+            if announce:
+                log(f"LED {role}: {iface_key} is empty, skipped")
+            continue
         d = os.path.join(cfg["sysfs_leds"], name)
         if not os.path.isdir(d):
             if announce:
@@ -142,17 +183,18 @@ def usable_leds(cfg, announce=False):
     return out
 
 
-def poll_once(cfg):
+def poll_once(cfg, now=None):
     """One evaluation of every usable LED. Returns the files written."""
-    want = wanted(cfg)
+    want = wanted(cfg, now)
     writes = []
     for role, d in usable_leds(cfg).items():
         trig, dev = want[role]
         try:
             w = apply_led(d, trig, dev)
         except OSError as e:
-            log(f"LED {role}: cannot set {trig}: {e}")
+            log_once(role, f"LED {role}: cannot set {trig}: {e}")
             continue
+        clear_log(role)
         if w:
             log(f"LED {role}: {trig}" + (f" {dev}" if dev else ""))
         writes += w
@@ -170,8 +212,10 @@ def main(argv):
         try:
             poll_once(cfg)
         except Exception as e:  # never die on a transient sysfs/state oddity
-            log(f"poll failed: {e}")
-        stop.wait(float(cfg["poll_interval_s"]))
+            log_once("poll", f"poll failed: {e}")
+        else:
+            clear_log("poll")
+        stop.wait(interval(cfg))
     log("van-leds stopping, LEDs left as they are")
     return 0