autoupdater: all fallback for situations with no valid time available

admin/autoupdater/files/usr/sbin/autoupdater

@@ -171,7 +171,19 @@ local function get_probability(date, priority)
   local diff = os.difftime(os.time(), date)
 
   if diff < 0 then
-    return 0
+    -- When the difference is negative, there are two possibilities: The manifest contains a wrong date, or our own clock is wrong.
+    -- As there isn't anything useful to do for an incorrect manifest, we'll assume the latter case and update anyways as we
+    -- can't do anything better
+    io.stderr:write('Warning: clock seems to be incorrect.\n')
+
+    if tonumber(fs.readfile('/proc/uptime'):match('^([^ ]+) ')) < 600 then
+      -- If the uptime is very low, it's possible we just didn't get the time over NTP yet, so we'll just wait until the next time the updater runs
+      return 0
+    else
+      -- Will give 1 when priority == 0, and lower probabilities the higher the priority value is
+      -- (similar to the old static probability system)
+      return 0.9^priority
+    end
   elseif diff >= seconds then
     return 1
   elseif oneshot then