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