From d6e77595ba45762b3c2dfdcd47a2d6b5b70154ae Mon Sep 17 00:00:00 2001
From: Joey Hess <joey@kitenet.net>
Date: Fri, 9 Mar 2012 19:08:10 -0400
Subject: factor out Utility.FileSystemEncoding

---
 Common.hs                     |  1 +
 Utility/FileSystemEncoding.hs | 23 +++++++++++++++++++++--
 Utility/Misc.hs               |  8 --------
 Utility/StatFS.hsc            |  5 ++---
 Utility/Touch.hsc             |  5 ++---
 5 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/Common.hs b/Common.hs
index cc6cf9252..347502460 100644
--- a/Common.hs
+++ b/Common.hs
@@ -26,5 +26,6 @@ import Utility.SafeCommand as X
 import Utility.Path as X
 import Utility.Directory as X
 import Utility.Monad as X
+import Utility.FileSystemEncoding as X
 
 import Utility.PartialPrelude as X
diff --git a/Utility/FileSystemEncoding.hs b/Utility/FileSystemEncoding.hs
index 6970a10de..048323ee3 100644
--- a/Utility/FileSystemEncoding.hs
+++ b/Utility/FileSystemEncoding.hs
@@ -1,4 +1,4 @@
-{- File system encoding handling.
+{- GHC File system encoding handling.
  -
  - Copyright 2012 Joey Hess <joey@kitenet.net>
  -
@@ -7,8 +7,17 @@
 
 module Utility.FileSystemEncoding where
 
-import GHC.IO.Encoding (getFileSystemEncoding)
+import System.IO
+import Foreign.C
 import GHC.Foreign as GHC
+import GHC.IO.Encoding
+
+{- 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". -}
+fileEncoding :: Handle -> IO ()
+fileEncoding h = hSetEncoding h =<< getFileSystemEncoding
 
 {- Marshal a Haskell FilePath into a NUL terminated C string using temporary
  - storage. The FilePath is encoded using the filesystem encoding,
@@ -16,3 +25,13 @@ import GHC.Foreign as GHC
  - was obtained. -}
 withFilePath :: FilePath -> (CString -> IO a) -> IO a
 withFilePath fp f = getFileSystemEncoding >>= \enc -> GHC.withCString enc fp f
+
+{- Encodes a FilePath into a String of encoded bytes, applying the
+ - filesystem encoding.
+ -
+ - This does not do any IO, beyond allocating a C buffer. GHC does not
+ - seem to provide a pure way to do this conversion. -}
+encodeFilePath :: FilePath -> IO String
+encodeFilePath fp = do
+	enc <- getFileSystemEncoding
+	GHC.withCString enc fp $ GHC.peekCString enc
diff --git a/Utility/Misc.hs b/Utility/Misc.hs
index 9c284c826..3ac5ca5c0 100644
--- a/Utility/Misc.hs
+++ b/Utility/Misc.hs
@@ -9,14 +9,6 @@ module Utility.Misc where
 
 import System.IO
 import Control.Monad
-import GHC.IO.Encoding
-
-{- 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 et. This special encoding
- - allows "arbitrary undecodable bytes to be round-tripped through it". -}
-fileEncoding :: Handle -> IO ()
-fileEncoding h = hSetEncoding h =<< getFileSystemEncoding
 
 {- A version of hgetContents that is not lazy. Ensures file is 
  - all read before it gets closed. -}
diff --git a/Utility/StatFS.hsc b/Utility/StatFS.hsc
index 51a6bda1e..58d0b3e02 100644
--- a/Utility/StatFS.hsc
+++ b/Utility/StatFS.hsc
@@ -47,15 +47,14 @@
 
 module Utility.StatFS ( FileSystemStats(..), getFileSystemStats ) where
 
+import Utility.FileSystemEncoding
+
 import Foreign
 import Foreign.C.Types
 import Foreign.C.String
 import GHC.IO.Encoding (getFileSystemEncoding)
 import GHC.Foreign as GHC
 
-withFilePath :: FilePath -> (CString -> IO a) -> IO a
-withFilePath fp f = getFileSystemEncoding >>= \enc -> GHC.withCString enc fp f
-
 #if defined (__FreeBSD__) || defined (__FreeBSD_kernel__) || defined (__APPLE__)
 # include <sys/param.h>
 # include <sys/mount.h>
diff --git a/Utility/Touch.hsc b/Utility/Touch.hsc
index 24ccd17a6..b84054cbc 100644
--- a/Utility/Touch.hsc
+++ b/Utility/Touch.hsc
@@ -13,15 +13,14 @@ module Utility.Touch (
 	touch
 ) where
 
+import Utility.FileSystemEncoding
+
 import Foreign
 import Foreign.C
 import Control.Monad (when)
 import GHC.IO.Encoding (getFileSystemEncoding)
 import GHC.Foreign as GHC
 
-withFilePath :: FilePath -> (CString -> IO a) -> IO a
-withFilePath fp f = getFileSystemEncoding >>= \enc -> GHC.withCString enc fp f
-
 newtype TimeSpec = TimeSpec CTime
 
 {- Changes the access and modification times of an existing file.
-- 
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