Always use filesystem encoding for all file and handle reads and writes.

This is a big scary change. I have convinced myself it should be safe. I
hope!

Utility/CoProcess.hs

@@ -47,10 +47,10 @@ start' s = do
 	rawMode to
 	return $ CoProcessState pid to from s
   where
-	rawMode h = do
-		fileEncoding h
 #ifdef mingw32_HOST_OS
-		hSetNewlineMode h noNewlineTranslation
+	rawMode h = hSetNewlineMode h noNewlineTranslation
+#else
+	rawMode _ = return ()
 #endif
 
 stop :: CoProcessHandle -> IO ()

Utility/ExternalSHA.hs

@@ -14,7 +14,6 @@ module Utility.ExternalSHA (externalSHA) where
 
 import Utility.SafeCommand
 import Utility.Process
-import Utility.FileSystemEncoding
 import Utility.Misc
 import Utility.Exception
 
@@ -30,7 +29,6 @@ externalSHA command shasize file = do
 		Left _ -> Left (command ++ " failed")
   where
 	readsha args = withHandle StdoutHandle createProcessSuccess p $ \h -> do
-		fileEncoding h
 		output  <- hGetContentsStrict h
 		hClose h
 		return output

Utility/FileSystemEncoding.hs

@@ -1,6 +1,6 @@
 {- GHC File system encoding handling.
  -
- - Copyright 2012-2014 Joey Hess <id@joeyh.name>
+ - Copyright 2012-2016 Joey Hess <id@joeyh.name>
  -
  - License: BSD-2-clause
  -}
@@ -9,7 +9,7 @@
 {-# OPTIONS_GHC -fno-warn-tabs #-}
 
 module Utility.FileSystemEncoding (
-	fileEncoding,
+	useFileSystemEncoding,
 	withFilePath,
 	md5FilePath,
 	decodeBS,
@@ -19,7 +19,6 @@ module Utility.FileSystemEncoding (
 	encodeW8NUL,
 	decodeW8NUL,
 	truncateFilePath,
-	setConsoleEncoding,
 ) where
 
 import qualified GHC.Foreign as GHC
@@ -39,19 +38,30 @@ import qualified Data.ByteString.Lazy.UTF8 as L8
 
 import Utility.Exception
 
-{- Sets a Handle to use the filesystem encoding. This causes data
- - written or read from it to be encoded/decoded the same
- - as ghc 7.4 does to filenames etc. This special encoding
- - allows "arbitrary undecodable bytes to be round-tripped through it".
+{- Makes all subsequent Handles that are opened, as well as stdio Handles,
+ - use the filesystem encoding, instead of the encoding of the current
+ - locale.
+ -
+ - The filesystem encoding allows "arbitrary undecodable bytes to be
+ - round-tripped through it". This avoids encoded failures when data is not
+ - encoded matching the current locale.
+ -
+ - Note that code can still use hSetEncoding to change the encoding of a
+ - Handle. This only affects the default encoding.
  -}
-fileEncoding :: Handle -> IO ()
+useFileSystemEncoding :: IO ()
+useFileSystemEncoding = do
 #ifndef mingw32_HOST_OS
-fileEncoding h = hSetEncoding h =<< Encoding.getFileSystemEncoding
+	e <- Encoding.getFileSystemEncoding
 #else
-{- The file system encoding does not work well on Windows,
- - and Windows only has utf FilePaths anyway. -}
-fileEncoding h = hSetEncoding h Encoding.utf8
+	{- The file system encoding does not work well on Windows,
+	 - and Windows only has utf FilePaths anyway. -}
+	let e = Encoding.utf8
 #endif
+	hSetEncoding stdin e
+	hSetEncoding stdout e
+	hSetEncoding stderr e
+	Encoding.setLocaleEncoding e	
 
 {- Marshal a Haskell FilePath into a NUL terminated C string using temporary
  - storage. The FilePath is encoded using the filesystem encoding,
@@ -165,10 +175,3 @@ truncateFilePath n = reverse . go [] n . L8.fromString
 					else go (c:coll) (cnt - x') (L8.drop 1 bs)
 			_ -> coll
 #endif
-
-{- This avoids ghc's output layer crashing on invalid encoded characters in
- - filenames when printing them out. -}
-setConsoleEncoding :: IO ()
-setConsoleEncoding = do
-	fileEncoding stdout
-	fileEncoding stderr

Utility/Lsof.hs

@@ -47,9 +47,8 @@ queryDir path = query ["+d", path]
  -}
 query :: [String] -> IO [(FilePath, LsofOpenMode, ProcessInfo)]
 query opts =
-	withHandle StdoutHandle (createProcessChecked checkSuccessProcess) p $ \h -> do
-		fileEncoding h
-		parse <$> hGetContentsStrict h
+	withHandle StdoutHandle (createProcessChecked checkSuccessProcess) p $
+		parse <$$> hGetContentsStrict
   where
 	p = proc "lsof" ("-F0can" : opts)
 

Utility/MagicWormhole.hs

@@ -27,7 +27,6 @@ import Utility.Process
 import Utility.SafeCommand
 import Utility.Monad
 import Utility.Misc
-import Utility.FileSystemEncoding
 import Utility.Env
 import Utility.Path
 
@@ -105,8 +104,7 @@ sendFile f (CodeObserver observer) ps = do
 	-- Work around stupid stdout buffering behavior of python.
 	-- See https://github.com/warner/magic-wormhole/issues/108
 	environ <- addEntry "PYTHONUNBUFFERED" "1" <$> getEnvironment
-	runWormHoleProcess p { env = Just environ} $ \_hin hout -> do
-		fileEncoding hout
+	runWormHoleProcess p { env = Just environ} $ \_hin hout ->
 		findcode =<< words <$> hGetContents hout
   where
 	p = wormHoleProcess (Param "send" : ps ++ [File f])

Utility/Misc.hs

@@ -10,9 +10,6 @@
 
 module Utility.Misc where
 
-import Utility.FileSystemEncoding
-import Utility.Monad
-
 import System.IO
 import Control.Monad
 import Foreign
@@ -35,20 +32,6 @@ hGetContentsStrict = hGetContents >=> \s -> length s `seq` return s
 readFileStrict :: FilePath -> IO String
 readFileStrict = readFile >=> \s -> length s `seq` return s
 
-{-  Reads a file strictly, and using the FileSystemEncoding, so it will
- -  never crash on a badly encoded file. -}
-readFileStrictAnyEncoding :: FilePath -> IO String
-readFileStrictAnyEncoding f = withFile f ReadMode $ \h -> do
-	fileEncoding h
-	hClose h `after` hGetContentsStrict h
-
-{- Writes a file, using the FileSystemEncoding so it will never crash
- - on a badly encoded content string. -}
-writeFileAnyEncoding :: FilePath -> String -> IO ()
-writeFileAnyEncoding f content = withFile f WriteMode $ \h -> do
-	fileEncoding h
-	hPutStr h content
-
 {- Like break, but the item matching the condition is not included
  - in the second result list.
  -

Utility/Quvi.hs

@@ -153,11 +153,8 @@ httponly :: QuviParams
 httponly Quvi04 = [Param "-c", Param "http"]
 httponly _ = [] -- No way to do it with 0.9?
 
-{- Both versions of quvi will output utf-8 encoded data even when
- - the locale doesn't support it. -}
 readQuvi :: [String] -> IO String
 readQuvi ps = withHandle StdoutHandle createProcessSuccess p $ \h -> do
-	fileEncoding h
 	r <- hGetContentsStrict h
 	hClose h
 	return r

Utility/Shell.hs

@@ -48,9 +48,8 @@ findShellCommand f = do
 #ifndef mingw32_HOST_OS
 	defcmd
 #else
-	l <- catchDefaultIO Nothing $ withFile f ReadMode $ \h -> do
-		fileEncoding h
-		headMaybe . lines <$> hGetContents h
+	l <- catchDefaultIO Nothing $ withFile f ReadMode $
+		headMaybe . lines <$$> hGetContents h
 	case l of
 		Just ('#':'!':rest) -> case words rest of
 			[] -> defcmd