continue conversion

Add Utility.OsString, with a special case for length.

Utility/OsString.hs

@@ -0,0 +1,32 @@
+{- OsString manipulation. Or ByteString when not built with OsString.
+ - Import qualified.
+ -
+ - Copyright 2025 Joey Hess <id@joeyh.name>
+ -
+ - License: BSD-2-clause
+ -}
+
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE PackageImports #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# OPTIONS_GHC -fno-warn-tabs #-}
+
+module Utility.OsString (
+	module X,
+	length
+) where
+
+#ifdef WITH_OSPATH
+import System.OsString as X hiding (length)
+import qualified System.OsString
+import qualified Data.ByteString as B
+import Utility.OsPath
+
+{- Avoid System.OsString.length, which returns the number of code points on
+ - windows. This is the number of bytes. -}
+length :: System.OsString.OsString -> Int
+length = B.length . fromOsString
+#else
+import Data.ByteString as X hiding (length)
+import Data.ByteString (length)
+#endif