diffusion change

gistfile1.txt

diff --git a/src/Data/Diffusion/Common.hs b/src/Data/Diffusion/Common.hs
index a86307a..a8d1850 100644
--- a/src/Data/Diffusion/Common.hs
+++ b/src/Data/Diffusion/Common.hs
@@ -18,6 +18,8 @@ import Data.Hashable (Hashable())
 import Data.Typeable (Typeable())
 import Data.Binary (Binary())
 import Control.DeepSeq (NFData)
+import Data.List (find)
+import Data.List (isPrefixOf)
 
 import GHC.IO.Exception (ExitCode (..))
 
@@ -44,15 +46,26 @@ curlCmd :: String -- ^ The URL to fetch
         -> Action ()
 curlCmd url destfile = cmd "curl" [url, "-s", "-o", destfile]
 
+isNewline :: Char -> Bool
+isNewline c = (c == '\r') || (c == '\n')
+
+rstrip :: [Char] -> [Char]
+rstrip = reverse . dropWhile isNewline . reverse
+
 -- | Fetches the ETag at the given URL. If no ETag is given by the server,
 --  we use the UTC Time that the file was retrieved, so the file will be pretty
 -- much downloaded every time.
 getEtag :: String -- ^ The URL of the file
         -> Action String -- ^ The Etag or UTC Time that this function was called
 getEtag url = do
-  (Exit c, Stdout out) <- cmd Shell $ "curl -I -L -s " ++ url ++ " | grep ETag"
-  case c of
-    ExitSuccess -> return out
-    ExitFailure _ -> do
+  (Exit c, Stdout out) <- cmd Shell $ "curl -I -L -s " ++ url
+  let etag = find (isPrefixOf "ETag") $ lines out
+
+  case (c, etag) of
+    (ExitSuccess, Just tag) -> return $ rstrip tag
+    (_, _)  -> handleFailure
+
+  where
+    handleFailure = do
       c' <- liftIO getCurrentTime
       return $ show c'
diff --git a/src/GenRegionMap.hs b/src/GenRegionMap.hs
index 4cf0f93..3b93307 100644
--- a/src/GenRegionMap.hs
+++ b/src/GenRegionMap.hs
@@ -13,7 +13,7 @@ opts = shakeOptions { shakeFiles     = dataDir
 buildMap :: IO ()
 buildMap = shakeArgs opts $ do
   etagOracle <- addOracle $ \(URL url) -> getEtag url
-  
+
   want [".diffusion/sub-map.osm.pbf"]
 
   ".diffusion/sub-map.osm.pbf" *> \_ -> do
@@ -31,10 +31,6 @@ buildMap = shakeArgs opts $ do
       , "file=\".diffusion/sub-map.osm.pbf\""
       ]
 
-  -- "etagtest" ~> do
-  --   r <- getEtag "http://download.geofabrik.de/south-america-latest.osm.pbf"
-  --   putNormal $ "hey got: " ++ show r
-
   "clean" ~> removeFilesAfter ".diffusion" ["//*"]
 
   ".diffusion/full-map.osm.pbf" *> \f -> do
@@ -49,7 +45,7 @@ buildMap = shakeArgs opts $ do
   ".diffusion/osmosis/bin/osmosis" *> \_ -> do
     need [".diffusion/osmosis-latest.tgz"]
     cmd "tar" ["xvzf", ".diffusion/osmosis-latest.tgz", "-C", ".diffusion/osmosis"]
-  
+
   ".diffusion/osmosis-latest.tgz" *> \f -> do
     ourl <- getReqEnv "OSMOSIS_URL"
     curlCmd ourl f