git-annex/Utility/Path/Windows.hs
2023-03-08 11:41:20 -04:00

47 lines
1.5 KiB
Haskell

{- Windows paths
-
- Copyright 2022-2023 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# LANGUAGE OverloadedStrings #-}
{-# OPTIONS_GHC -fno-warn-tabs #-}
module Utility.Path.Windows (
convertToWindowsNativeNamespace
) where
import Utility.Path
import Utility.FileSystemEncoding
import System.FilePath.ByteString (combine)
import qualified Data.ByteString as B
import qualified System.FilePath.Windows.ByteString as P
import System.Directory (getCurrentDirectory)
{- Convert a filepath to use Windows's native namespace.
- This avoids filesystem length limits.
-
- This is similar to the way base converts filenames on windows,
- but as that is implemented in C (create_device_name) and not
- exported, it cannot be used here. Several edge cases are not handled,
- including network shares and dos short paths.
-}
convertToWindowsNativeNamespace :: RawFilePath -> IO RawFilePath
convertToWindowsNativeNamespace f
| win32_dev_namespace `B.isPrefixOf` f = return f
| win32_file_namespace `B.isPrefixOf` f = return f
| nt_device_namespace `B.isPrefixOf` f = return f
| otherwise = do
-- Make absolute because any '.' and '..' in the path
-- will not be resolved once it's converted.
cwd <- toRawFilePath <$> getCurrentDirectory
let p = simplifyPath (combine cwd f)
-- Normalize slashes.
let p' = P.normalise p
return (win32_file_namespace <> p')
where
win32_dev_namespace = "\\\\.\\"
win32_file_namespace = "\\\\?\\"
nt_device_namespace = "\\Device\\"