158 lines
4.3 KiB
Haskell
158 lines
4.3 KiB
Haskell
{- File mode utilities.
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-
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- Copyright 2010-2012 Joey Hess <joey@kitenet.net>
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-
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- License: BSD-2-clause
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-}
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{-# LANGUAGE CPP #-}
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module Utility.FileMode where
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import System.IO
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import Control.Monad
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import Control.Exception (bracket)
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import System.PosixCompat.Types
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import Utility.PosixFiles
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#ifndef mingw32_HOST_OS
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import System.Posix.Files
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#endif
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import Foreign (complement)
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import Utility.Exception
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{- Applies a conversion function to a file's mode. -}
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modifyFileMode :: FilePath -> (FileMode -> FileMode) -> IO ()
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modifyFileMode f convert = void $ modifyFileMode' f convert
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modifyFileMode' :: FilePath -> (FileMode -> FileMode) -> IO FileMode
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modifyFileMode' f convert = do
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s <- getFileStatus f
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let old = fileMode s
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let new = convert old
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when (new /= old) $
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setFileMode f new
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return old
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{- Adds the specified FileModes to the input mode, leaving the rest
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- unchanged. -}
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addModes :: [FileMode] -> FileMode -> FileMode
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addModes ms m = combineModes (m:ms)
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{- Removes the specified FileModes from the input mode. -}
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removeModes :: [FileMode] -> FileMode -> FileMode
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removeModes ms m = m `intersectFileModes` complement (combineModes ms)
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{- Runs an action after changing a file's mode, then restores the old mode. -}
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withModifiedFileMode :: FilePath -> (FileMode -> FileMode) -> IO a -> IO a
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withModifiedFileMode file convert a = bracket setup cleanup go
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where
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setup = modifyFileMode' file convert
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cleanup oldmode = modifyFileMode file (const oldmode)
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go _ = a
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writeModes :: [FileMode]
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writeModes = [ownerWriteMode, groupWriteMode, otherWriteMode]
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readModes :: [FileMode]
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readModes = [ownerReadMode, groupReadMode, otherReadMode]
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executeModes :: [FileMode]
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executeModes = [ownerExecuteMode, groupExecuteMode, otherExecuteMode]
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otherGroupModes :: [FileMode]
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otherGroupModes =
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[ groupReadMode, otherReadMode
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, groupWriteMode, otherWriteMode
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]
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{- Removes the write bits from a file. -}
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preventWrite :: FilePath -> IO ()
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preventWrite f = modifyFileMode f $ removeModes writeModes
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{- Turns a file's owner write bit back on. -}
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allowWrite :: FilePath -> IO ()
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allowWrite f = modifyFileMode f $ addModes [ownerWriteMode]
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{- Turns a file's owner read bit back on. -}
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allowRead :: FilePath -> IO ()
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allowRead f = modifyFileMode f $ addModes [ownerReadMode]
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{- Allows owner and group to read and write to a file. -}
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groupSharedModes :: [FileMode]
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groupSharedModes =
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[ ownerWriteMode, groupWriteMode
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, ownerReadMode, groupReadMode
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]
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groupWriteRead :: FilePath -> IO ()
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groupWriteRead f = modifyFileMode f $ addModes groupSharedModes
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checkMode :: FileMode -> FileMode -> Bool
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checkMode checkfor mode = checkfor `intersectFileModes` mode == checkfor
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{- Checks if a file mode indicates it's a symlink. -}
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isSymLink :: FileMode -> Bool
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#ifdef mingw32_HOST_OS
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isSymLink _ = False
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#else
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isSymLink = checkMode symbolicLinkMode
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#endif
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{- Checks if a file has any executable bits set. -}
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isExecutable :: FileMode -> Bool
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isExecutable mode = combineModes executeModes `intersectFileModes` mode /= 0
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{- Runs an action without that pesky umask influencing it, unless the
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- passed FileMode is the standard one. -}
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noUmask :: FileMode -> IO a -> IO a
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#ifndef mingw32_HOST_OS
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noUmask mode a
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| mode == stdFileMode = a
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| otherwise = withUmask nullFileMode a
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#else
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noUmask _ a = a
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#endif
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withUmask :: FileMode -> IO a -> IO a
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#ifndef mingw32_HOST_OS
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withUmask umask a = bracket setup cleanup go
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where
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setup = setFileCreationMask umask
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cleanup = setFileCreationMask
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go _ = a
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#else
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withUmask _ a = a
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#endif
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combineModes :: [FileMode] -> FileMode
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combineModes [] = undefined
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combineModes [m] = m
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combineModes (m:ms) = foldl unionFileModes m ms
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isSticky :: FileMode -> Bool
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#ifdef mingw32_HOST_OS
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isSticky _ = False
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#else
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isSticky = checkMode stickyMode
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stickyMode :: FileMode
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stickyMode = 512
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setSticky :: FilePath -> IO ()
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setSticky f = modifyFileMode f $ addModes [stickyMode]
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#endif
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{- Writes a file, ensuring that its modes do not allow it to be read
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- or written by anyone other than the current user,
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- before any content is written.
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-
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- When possible, this is done using the umask.
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-
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- On a filesystem that does not support file permissions, this is the same
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- as writeFile.
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-}
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writeFileProtected :: FilePath -> String -> IO ()
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writeFileProtected file content = withUmask 0o0077 $
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withFile file WriteMode $ \h -> do
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void $ tryIO $ modifyFileMode file $ removeModes otherGroupModes
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hPutStr h content
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