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|
{- File mode utilities.
-
- Copyright 2010-2012 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# LANGUAGE CPP #-}
module Utility.FileMode where
import System.IO
import Control.Monad
import System.PosixCompat.Types
import Utility.PosixFiles
#ifndef mingw32_HOST_OS
import System.Posix.Files
#endif
import Foreign (complement)
import Utility.Exception
{- Applies a conversion function to a file's mode. -}
modifyFileMode :: FilePath -> (FileMode -> FileMode) -> IO ()
modifyFileMode f convert = do
s <- getFileStatus f
let old = fileMode s
let new = convert old
when (new /= old) $
setFileMode f new
{- 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)
writeModes :: [FileMode]
writeModes = [ownerWriteMode, groupWriteMode, otherWriteMode]
readModes :: [FileMode]
readModes = [ownerReadMode, groupReadMode, otherReadMode]
executeModes :: [FileMode]
executeModes = [ownerExecuteMode, groupExecuteMode, otherExecuteMode]
otherGroupModes :: [FileMode]
otherGroupModes =
[ groupReadMode, otherReadMode
, groupWriteMode, otherWriteMode
]
{- 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]
{- Turns a file's owner read bit back on. -}
allowRead :: FilePath -> IO ()
allowRead f = modifyFileMode f $ addModes [ownerReadMode]
{- Allows owner and group to read and write to a file. -}
groupSharedModes :: [FileMode]
groupSharedModes =
[ ownerWriteMode, groupWriteMode
, ownerReadMode, groupReadMode
]
groupWriteRead :: FilePath -> IO ()
groupWriteRead f = modifyFileMode f $ addModes groupSharedModes
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 = withUmask nullFileMode a
#else
noUmask _ a = a
#endif
withUmask :: FileMode -> IO a -> IO a
#ifndef mingw32_HOST_OS
withUmask umask a = bracket setup cleanup go
where
setup = setFileCreationMask umask
cleanup = setFileCreationMask
go _ = a
#else
withUmask _ a = a
#endif
combineModes :: [FileMode] -> FileMode
combineModes [] = 0
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
- or written by anyone other than the current user,
- before any content is written.
-
- When possible, this is done using the umask.
-
- On a filesystem that does not support file permissions, this is the same
- as writeFile.
-}
writeFileProtected :: FilePath -> String -> IO ()
writeFileProtected file content = writeFileProtected' file
(\h -> hPutStr h content)
writeFileProtected' :: FilePath -> (Handle -> IO ()) -> IO ()
writeFileProtected' file writer = withUmask 0o0077 $
withFile file WriteMode $ \h -> do
void $ tryIO $ modifyFileMode file $ removeModes otherGroupModes
writer h
|
