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diff --git a/Utility/Touch.hsc b/Utility/Touch.hsc
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+{- More control over touching a file.
+ -
+ - Copyright 2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+{-# LANGUAGE ForeignFunctionInterface #-}
+
+module Utility.Touch (
+	TimeSpec(..),
+	touchBoth,
+	touch
+) where
+
+import Foreign
+import Foreign.C
+import Control.Monad (when)
+
+newtype TimeSpec = TimeSpec CTime
+
+{- Changes the access and modification times of an existing file.
+   Can follow symlinks, or not. Throws IO error on failure. -}
+touchBoth :: FilePath -> TimeSpec -> TimeSpec -> Bool -> IO ()
+
+touch :: FilePath -> TimeSpec -> Bool -> IO ()
+touch file mtime follow = touchBoth file mtime mtime follow
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/time.h>
+
+#ifndef _BSD_SOURCE
+#define _BSD_SOURCE
+#endif
+
+#if (defined UTIME_OMIT && defined UTIME_NOW && defined AT_FDCWD && defined AT_SYMLINK_NOFOLLOW)
+
+at_fdcwd :: CInt
+at_fdcwd = #const AT_FDCWD
+
+at_symlink_nofollow :: CInt
+at_symlink_nofollow = #const AT_SYMLINK_NOFOLLOW
+
+instance Storable TimeSpec where
+	-- use the larger alignment of the two types in the struct
+	alignment _ = max sec_alignment nsec_alignment
+		where
+			sec_alignment = alignment (undefined::CTime)
+			nsec_alignment = alignment (undefined::CLong)
+	sizeOf _ = #{size struct timespec}
+	peek ptr = do
+		sec <- #{peek struct timespec, tv_sec} ptr
+		return $ TimeSpec sec
+	poke ptr (TimeSpec sec) = do
+		#{poke struct timespec, tv_sec} ptr sec
+		#{poke struct timespec, tv_nsec} ptr (0 :: CLong)
+
+{- While its interface is beastly, utimensat is in recent
+   POSIX standards, unlike lutimes. -}
+foreign import ccall "utimensat" 
+	c_utimensat :: CInt -> CString -> Ptr TimeSpec -> CInt -> IO CInt
+
+touchBoth file atime mtime follow = 
+	allocaArray 2 $ \ptr ->
+	withCString file $ \f -> do
+		pokeArray ptr [atime, mtime]
+		r <- c_utimensat at_fdcwd f ptr flags
+		when (r /= 0) $ throwErrno "touchBoth"
+	where
+		flags = if follow
+			then 0
+			else at_symlink_nofollow 
+
+#else
+#if 0
+{- Using lutimes is needed for BSD.
+ - 
+ - TODO: test if lutimes is available. May have to do it in configure.
+ - TODO: TimeSpec uses a CTime, while tv_sec is a CLong. It is implementation
+ - dependent whether these are the same; need to find a cast that works.
+ - (Without the cast it works on linux i386, but
+ - maybe not elsewhere.)
+ -}
+
+instance Storable TimeSpec where
+	alignment _ = alignment (undefined::CLong)
+	sizeOf _ = #{size struct timeval}
+	peek ptr = do
+		sec <- #{peek struct timeval, tv_sec} ptr
+		return $ TimeSpec sec
+	poke ptr (TimeSpec sec) = do
+		#{poke struct timeval, tv_sec} ptr sec
+		#{poke struct timeval, tv_usec} ptr (0 :: CLong) 
+
+foreign import ccall "utimes" 
+	c_utimes :: CString -> Ptr TimeSpec -> IO CInt
+foreign import ccall "lutimes" 
+	c_lutimes :: CString -> Ptr TimeSpec -> IO CInt
+
+touchBoth file atime mtime follow = 
+	allocaArray 2 $ \ptr ->
+	withCString file $ \f -> do
+		pokeArray ptr [atime, mtime]
+		r <- syscall f ptr
+		if (r /= 0)
+			then throwErrno "touchBoth"
+			else return ()
+	where
+		syscall = if follow
+			then c_lutimes
+			else c_utimes
+
+#else
+#warning "utimensat and lutimes not available; building without symlink timestamp preservation support"
+touchBoth _ _ _ _ = return ()
+#endif
+#endif