Neither path may refer to an existing directory.
-}
copyFile :: FilePath -> FilePath -> IO ()
-copyFile fromFPath toFPath =
+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.
#if (!(defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ > 600))
- do readFile fromFPath >>= writeFile toFPath
- try (copyPermissions fromFPath toFPath)
- return ()
+ contents <- readFile fromFPath
+ try (removeFile toFPath)
+ writeFile toFPath contents
+ try (copyPermissions fromFPath toFPath)
+ return ()
#else
- (bracket (openBinaryFile fromFPath ReadMode) hClose $ \hFrom ->
- bracket (openBinaryFile toFPath WriteMode) hClose $ \hTo ->
+ (bracket (openBinaryFile fromFPath ReadMode) hClose $ \hFrom -> do
+ try (removeFile toFPath)
+ bracket (openBinaryFile toFPath WriteMode) hClose $ \hTo -> do
allocaBytes bufferSize $ \buffer -> do
copyContents hFrom hTo buffer
try (copyPermissions fromFPath toFPath)