Release Vulpes OS 2.7-preview.22

tundra/runtime/clock-state.py

@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: MPL-2.0
+"""Preserve wall time across boots when Qualcomm's RTC has no Unix epoch."""
+import json
+from pathlib import Path
+import time
+
+STATE = Path('/var/lib/tundra/clock/last-time.json')
+RTC = Path('/sys/class/rtc/rtc0/since_epoch')
+
+
+def rtc_seconds():
+    try:
+        return int(RTC.read_text().strip())
+    except (OSError, ValueError):
+        return None
+
+
+def valid_epoch(value):
+    return type(value) in (int, float) and 946684800 <= value <= 4102444800
+
+
+def restore():
+    try:
+        saved = json.loads(STATE.read_text())
+        epoch, previous = saved['epoch'], saved.get('rtc')
+        if not valid_epoch(epoch):
+            return False
+        current = rtc_seconds()
+        # A reset/replaced RTC is not evidence of time elapsed while powered off.
+        if type(previous) is int and current is not None and 0 <= current - previous <= 366*86400:
+            epoch += current - previous
+        if valid_epoch(epoch) and time.time() < epoch:
+            time.clock_settime(time.CLOCK_REALTIME, epoch)
+            return True
+    except (OSError, ValueError, KeyError, TypeError):
+        pass
+    return False
+
+
+def save():
+    epoch = time.time()
+    if not valid_epoch(epoch):
+        return
+    STATE.parent.mkdir(parents=True, exist_ok=True)
+    temporary = STATE.with_suffix('.tmp')
+    temporary.write_text(json.dumps({'epoch': epoch, 'rtc': rtc_seconds()}) + '\n')
+    temporary.chmod(0o600)
+    temporary.replace(STATE)
+
+
+if __name__ == '__main__':
+    import sys
+    if sys.argv[1:] == ['--restore']:
+        restore()
+    elif sys.argv[1:] == ['--save']:
+        save()
+    else:
+        raise SystemExit('Use --restore or --save')