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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 Touch (
TimeSpec(..),
nowTime,
omitTime,
touchBoth,
touch
) where
import Foreign
import Foreign.C
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#ifndef _POSIX_C_SOURCE
#define _POSIX_C_SOURCE >= 200809L
#endif
data TimeSpec = TimeSpec CTime CLong
touch :: FilePath -> TimeSpec -> Bool -> IO ()
touch file mtime follow = touchBoth file omitTime mtime follow
touchBoth :: FilePath -> TimeSpec -> TimeSpec -> Bool -> IO ()
omitTime :: TimeSpec
nowTime :: TimeSpec
#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
omitTime = TimeSpec 0 #const UTIME_OMIT
nowTime = TimeSpec 0 #const UTIME_NOW
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
nsec <- #{peek struct timespec, tv_nsec} ptr
return $ TimeSpec sec nsec
poke ptr (TimeSpec sec nsec) = do
#{poke struct timespec, tv_sec} ptr sec
#{poke struct timespec, tv_nsec} ptr nsec
{- While its interface is beastly, utimensat is in recent
POSIX standards, unlike futimes. -}
foreign import ccall "utimensat"
c_utimensat :: CInt -> CString -> Ptr TimeSpec -> CInt -> IO CInt
{- Changes the access and/or modification times of an existing file.
Can follow symlinks, or not. Throws IO error on failure. -}
touchBoth file atime mtime follow =
allocaArray 2 $ \ptr ->
withCString file $ \f -> do
pokeArray ptr [atime, mtime]
r <- c_utimensat at_fdcwd f ptr flags
if (r /= 0)
then throwErrno "touchBoth"
else return ()
where
flags = if follow
then 0
else at_symlink_nofollow
#else
#warning "utimensat not available; building without symlink timestamp preservation support"
omitTime = TimeSpec 0 (-1)
nowTime = TimeSpec 0 (-2)
touchBoth _ _ _ _ = return ()
#endif
|
