From 99db29942570e5acf82c236757b62253c1c6f803 Mon Sep 17 00:00:00 2001
From: Jose Antonio Ortega Ruiz <jao@gnu.org>
Date: Thu, 3 Nov 2011 18:33:34 +0100
Subject: Battery monitor: better handling of exceptions
An attempt to fix #60, that is, crashes after power resumes due to
unreadable battery stats files.
---
src/Plugins/Monitors/Batt.hs | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/src/Plugins/Monitors/Batt.hs b/src/Plugins/Monitors/Batt.hs
index c276e6b..dfa8075 100644
--- a/src/Plugins/Monitors/Batt.hs
+++ b/src/Plugins/Monitors/Batt.hs
@@ -15,12 +15,14 @@
module Plugins.Monitors.Batt ( battConfig, runBatt, runBatt' ) where
-import qualified Data.ByteString.Lazy.Char8 as B
+import Control.Exception (SomeException, handle)
import Plugins.Monitors.Common
import System.FilePath ((</>))
import System.Posix.Files (fileExist)
import System.Console.GetOpt
+import qualified Data.ByteString.Lazy.Char8 as B
+
data BattOpts = BattOpts
{ onString :: String
, offString :: String
@@ -107,11 +109,9 @@ batteryFiles bat =
haveAc :: FilePath -> IO Bool
haveAc f = do
- exists <- fileExist ofile
- if exists
- then fmap ((== "1\n") . B.unpack) (B.readFile ofile)
- else return False
+ handle onError (fmap ((== "1\n") . B.unpack) (B.readFile ofile))
where ofile = sysDir </> f
+ onError = const (return False) :: SomeException -> IO Bool
readBattery :: Files -> IO Battery
readBattery NoFiles = return $ Battery 0 0 0 0
@@ -124,7 +124,8 @@ readBattery files =
(3600 * b / 1000000) -- wattseconds
(c / 1000000) -- volts
(if c > 0 then (d / c) else -1) -- amperes
- where grab f = catch (fmap (read . B.unpack) $ B.readFile f) (\_ -> return 0)
+ where grab f = handle onError (fmap (read . B.unpack) $ B.readFile f)
+ onError = const (return 0) :: SomeException -> IO Float
readBatteries :: BattOpts -> [Files] -> IO Result
readBatteries opts bfs =
--
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