transactional refreshCache function in cokiki

1 files changed, 16 insertions, 4 deletions

diff --git a/lib/Kiki.hs b/lib/Kiki.hs
index 0e06ee2..34594cc 100644
--- a/lib/Kiki.hs
+++ b/lib/Kiki.hs
@@ -18,8 +18,10 @@ import Data.Ord
 import System.Directory
 import System.FilePath.Posix
 import System.IO
+import System.IO.Temp
 import System.Posix.User
 import System.Process
+import System.Posix.Files
 import qualified Codec.Binary.Base64 as Base64
 import qualified Data.ByteString.Lazy as L
 import qualified Data.ByteString.Lazy.Char8 as Char8
@@ -212,9 +214,19 @@ importAndRefresh root cmn = do
 refreshCache :: KeyRingRuntime -> Maybe FilePath -> IO ()
 refreshCache rt rootdir = do
 
-    let mkpath pth = fromMaybe "" rootdir ++ "/var/cache/kiki/"++pth
-
-        write' wr f bs = do
+    let getMkPathAndCommit destdir = do
+        let cachedir = takeDirectory destdir
+            unslash ('/':xs) = xs
+            unslash xs = xs
+        createDirectoryIfMissing True cachedir
+        tmpdir <- createTempDirectory cachedir "tmp.dir"
+        createSymbolicLink tmpdir (tmpdir ++ ".link")
+        let mkpath pth = tmpdir </> unslash pth
+            commit     = rename (tmpdir ++ ".link") destdir
+        return (mkpath,commit)
+    (mkpath, commit) <- getMkPathAndCommit (fromMaybe "" rootdir ++ "/var/cache/kiki/config")
+
+    let write' wr f bs = do
             createDirectoryIfMissing True $ takeDirectory f
             wr f bs
         write = write' writeFile
@@ -347,7 +359,7 @@ refreshCache rt rootdir = do
             , "  auto=route"
             , ""
             ] ++ filter (not . Char8.null) cons
-    return ()
+    commit
 
 strongswanForContact addr oname = Char8.unlines
     [ "conn " <> p oname