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|
{- File mode utilities.
-
- Copyright 2010-2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Utility.FileMode where
import Common
import Control.Exception (bracket)
import System.PosixCompat.Types
#ifndef mingw32_HOST_OS
import System.Posix.Files
#endif
import Foreign (complement)
{- Applies a conversion function to a file's mode. -}
modifyFileMode :: FilePath -> (FileMode -> FileMode) -> IO ()
modifyFileMode f convert = void $ modifyFileMode' f convert
modifyFileMode' :: FilePath -> (FileMode -> FileMode) -> IO FileMode
modifyFileMode' f convert = do
s <- getFileStatus f
let old = fileMode s
let new = convert old
when (new /= old) $
setFileMode f new
return old
{- Adds the specified FileModes to the input mode, leaving the rest
- unchanged. -}
addModes :: [FileMode] -> FileMode -> FileMode
addModes ms m = combineModes (m:ms)
{- Removes the specified FileModes from the input mode. -}
removeModes :: [FileMode] -> FileMode -> FileMode
removeModes ms m = m `intersectFileModes` complement (combineModes ms)
{- Runs an action after changing a file's mode, then restores the old mode. -}
withModifiedFileMode :: FilePath -> (FileMode -> FileMode) -> IO a -> IO a
withModifiedFileMode file convert a = bracket setup cleanup go
where
setup = modifyFileMode' file convert
cleanup oldmode = modifyFileMode file (const oldmode)
go _ = a
writeModes :: [FileMode]
writeModes = [ownerWriteMode, groupWriteMode, otherWriteMode]
readModes :: [FileMode]
readModes = [ownerReadMode, groupReadMode, otherReadMode]
executeModes :: [FileMode]
executeModes = [ownerExecuteMode, groupExecuteMode, otherExecuteMode]
{- Removes the write bits from a file. -}
preventWrite :: FilePath -> IO ()
preventWrite f = modifyFileMode f $ removeModes writeModes
{- Turns a file's owner write bit back on. -}
allowWrite :: FilePath -> IO ()
allowWrite f = modifyFileMode f $ addModes [ownerWriteMode]
{- Allows owner and group to read and write to a file. -}
groupWriteRead :: FilePath -> IO ()
groupWriteRead f = modifyFileMode f $ addModes
[ ownerWriteMode, groupWriteMode
, ownerReadMode, groupReadMode
]
checkMode :: FileMode -> FileMode -> Bool
checkMode checkfor mode = checkfor `intersectFileModes` mode == checkfor
{- Checks if a file mode indicates it's a symlink. -}
isSymLink :: FileMode -> Bool
#ifdef mingw32_HOST_OS
isSymLink _ = False
#else
isSymLink = checkMode symbolicLinkMode
#endif
{- Checks if a file has any executable bits set. -}
isExecutable :: FileMode -> Bool
isExecutable mode = combineModes executeModes `intersectFileModes` mode /= 0
{- Runs an action without that pesky umask influencing it, unless the
- passed FileMode is the standard one. -}
noUmask :: FileMode -> IO a -> IO a
#ifndef mingw32_HOST_OS
noUmask mode a
| mode == stdFileMode = a
| otherwise = bracket setup cleanup go
where
setup = setFileCreationMask nullFileMode
cleanup = setFileCreationMask
go _ = a
#else
noUmask _ a = a
#endif
combineModes :: [FileMode] -> FileMode
combineModes [] = undefined
combineModes [m] = m
combineModes (m:ms) = foldl unionFileModes m ms
isSticky :: FileMode -> Bool
#ifdef mingw32_HOST_OS
isSticky _ = False
#else
isSticky = checkMode stickyMode
stickyMode :: FileMode
stickyMode = 512
setSticky :: FilePath -> IO ()
setSticky f = modifyFileMode f $ addModes [stickyMode]
#endif
{- Writes a file, ensuring that its modes do not allow it to be read
- by anyone other than the current user, before any content is written.
-
- On a filesystem that does not support file permissions, this is the same
- as writeFile.
-}
writeFileProtected :: FilePath -> String -> IO ()
writeFileProtected file content = do
h <- openFile file WriteMode
void $ tryIO $
modifyFileMode file $
removeModes [groupReadMode, otherReadMode]
hPutStr h content
hClose h
|
