git-annex/Utility/FileMode.hs
Joey Hess 14971414dc
Make test suite work better when the temp directory is on NFS.
Deleting directories is one of the great unsolved problems of CS, thanks to
abominations like NFS lock files and Windows and races with other processes
cleaning up after themselves in the background. The gpg test harness
sometimes failed to delete its temp directory on NFS. Avoid the problem
class by not deleting it at all, and putting it inside the tmp repo being
tested. The test suite's more robust (and/or nonsensical) workarounds for
deleting its test dir will thus be used, hopefully avoiding the problem
until an OS finds a new way to violate POSIX and the laws of nature.

Note that this means that the .gnupg directory will be on whatever
filesystem the test suite is being run on, which may be a lesser quality
filesystem than gpg is really expecting. Gpg does not seem to need to
write sockets etc to there so this seems ok. The only known problem is
that if the filesystem forces a directory mode like 777, gpg will warn
about unsafe home directory perms, but it still works.
2018-12-19 12:44:56 -04:00

187 lines
5.1 KiB
Haskell

{- File mode utilities.
-
- Copyright 2010-2017 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# LANGUAGE CPP #-}
module Utility.FileMode (
module Utility.FileMode,
FileMode,
) where
import System.IO
import Control.Monad
import System.PosixCompat.Types
import System.PosixCompat.Files
#ifndef mingw32_HOST_OS
import System.Posix.Files (symbolicLinkMode)
import Control.Monad.IO.Class (liftIO)
#endif
import Control.Monad.IO.Class (MonadIO)
import Foreign (complement)
import Control.Monad.Catch
import Utility.Exception
{- 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
{- 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
{- 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
, 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]
{- 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 :: (MonadIO m, MonadMask m) => FileMode -> m a -> m a
#ifndef mingw32_HOST_OS
noUmask mode a
| mode == stdFileMode = a
| otherwise = withUmask nullFileMode a
#else
noUmask _ a = a
#endif
withUmask :: (MonadIO m, MonadMask m) => FileMode -> m a -> m a
#ifndef mingw32_HOST_OS
withUmask umask a = bracket setup cleanup go
where
setup = liftIO $ setFileCreationMask umask
cleanup = liftIO . setFileCreationMask
go _ = a
#else
withUmask _ a = a
#endif
getUmask :: IO FileMode
#ifndef mingw32_HOST_OS
getUmask = bracket setup cleanup return
where
setup = setFileCreationMask nullFileMode
cleanup = setFileCreationMask
#else
getUmask = return nullFileMode
#endif
defaultFileMode :: IO FileMode
defaultFileMode = do
umask <- getUmask
return $ intersectFileModes (complement umask) stdFileMode
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 = protectedOutput $
withFile file WriteMode $ \h -> do
void $ tryIO $ modifyFileMode file $ removeModes otherGroupModes
writer h
protectedOutput :: IO a -> IO a
protectedOutput = withUmask 0o0077