Allow recovery from missing thermal zones

Sometimes the kernel takes some time to populate /sys/class/thermal/ * after
resuming from suspend. Previously, this would result in the thermal plugin
dying permanantly. With this patch, we show "0" until the kernel gets around to
populating the sysfs nodes we need.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/Plugins/Monitors/ThermalZone.hs b/src/Plugins/Monitors/ThermalZone.hs
index d692191..838a7f5 100644
--- a/src/Plugins/Monitors/ThermalZone.hs
+++ b/src/Plugins/Monitors/ThermalZone.hs
@@ -20,6 +20,7 @@ module Plugins.Monitors.ThermalZone (thermalZoneConfig, runThermalZone) where
 import Plugins.Monitors.Common
 
 import System.Posix.Files (fileExist)
+import Control.Exception (IOException, catch)
 import qualified Data.ByteString.Char8 as B
 
 -- | Default thermal configuration.
@@ -33,10 +34,12 @@ runThermalZone :: [String] -> Monitor String
 runThermalZone args = do
     let zone = head args
         file = "/sys/class/thermal/thermal_zone" ++ zone ++ "/temp"
+        handleIOError :: IOException -> IO B.ByteString
+        handleIOError _ = return (B.pack "-1")
         parse = return . (read :: String -> Int) . B.unpack
     exists <- io $ fileExist file
     if exists
-      then do mdegrees <- io $ B.readFile file >>= parse
+      then do mdegrees <- io $ catch ( B.readFile file) handleIOError >>= parse
               temp <- showWithColors show (mdegrees `quot` 1000)
               parseTemplate [ temp ]
       else getConfigValue naString