copyFile: try removing the target file before opening it for writing

diff --git a/System/Directory.hs b/System/Directory.hs
index 5e87c21..bdd7f3c 100644 (file)
--- a/System/Directory.hs
+++ b/System/Directory.hs
@@ -510,23 +510,14 @@ If the /new/ file already exists, it is atomically replaced by the /old/ file.
 Neither path may refer to an existing directory.
 -}
 copyFile :: FilePath -> FilePath -> IO ()
-copyFile fromFPath toFPath = do
-       -- We try removing the target file before opening it for
-       -- writing.  In the event that the target file is locked or in
-       -- use, this allows us to replace it safely.  However, it
-       -- leaves a race condition: someone else might create the file
-       -- after we delete it, but there isn't much we can do about
-       -- that.
+copyFile fromFPath toFPath =
 #if (!(defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ > 600))
-       contents <- readFile fromFPath
-       try (removeFile toFPath)
-       writeFile toFPath contents
-       try (copyPermissions fromFPath toFPath)
-       return ()
+       do readFile fromFPath >>= writeFile toFPath
+          try (copyPermissions fromFPath toFPath)
+          return ()
 #else
-       (bracket (openBinaryFile fromFPath ReadMode) hClose $ \hFrom -> do
-        try (removeFile toFPath)
-        bracket (openBinaryFile toFPath WriteMode) hClose $ \hTo -> do
+       (bracket (openBinaryFile fromFPath ReadMode) hClose $ \hFrom ->
+        bracket (openBinaryFile toFPath WriteMode) hClose $ \hTo ->
         allocaBytes bufferSize $ \buffer -> do
                copyContents hFrom hTo buffer
                try (copyPermissions fromFPath toFPath)