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|
{- More control over touching a file.
-
- Copyright 2011 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# LANGUAGE ForeignFunctionInterface #-}
module Utility.Touch (
TimeSpec(..),
touchBoth,
touch
) where
#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)
#define use_utimensat 1
import Utility.FileSystemEncoding
import Control.Monad (when)
import Foreign
#endif
import Foreign.C
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 = touchBoth file mtime mtime
#ifdef use_utimensat
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 ->
withFilePath file $ \f -> do
pokeArray ptr [atime, mtime]
r <- c_utimensat at_fdcwd f ptr flags
when (r /= 0) $ throwErrno "touchBoth"
where
flags
| follow = 0
| otherwise = 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 ->
withFilePath file $ \f -> do
pokeArray ptr [atime, mtime]
r <- syscall f ptr
when (r /= 0) $
throwErrno "touchBoth"
where
syscall
| follow = c_lutimes
| otherwise = c_utimes
#else
#warning "utimensat and lutimes not available; building without symlink timestamp preservation support"
touchBoth _ _ _ _ = return ()
#endif
#endif
|
