git-annex/Utility/Tmp.hs

124 lines
4.1 KiB
Haskell

{- Temporary files and directories.
-
- Copyright 2010-2013 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# LANGUAGE CPP #-}
{-# OPTIONS_GHC -fno-warn-tabs #-}
module Utility.Tmp where
import System.IO
import Control.Monad.IfElse
import System.FilePath
import System.Directory
import Control.Monad.IO.Class
#ifndef mingw32_HOST_OS
import System.Posix.Temp (mkdtemp)
#endif
import Utility.Exception
import Utility.FileSystemEncoding
import Utility.PosixFiles
type Template = String
{- Runs an action like writeFile, writing to a temp file first and
- then moving it into place. The temp file is stored in the same
- directory as the final file to avoid cross-device renames. -}
viaTmp :: (MonadMask m, MonadIO m) => (FilePath -> String -> m ()) -> FilePath -> String -> m ()
viaTmp a file content = bracketIO setup cleanup use
where
(dir, base) = splitFileName file
template = base ++ ".tmp"
setup = do
createDirectoryIfMissing True dir
openTempFile dir template
cleanup (tmpfile, h) = do
_ <- tryIO $ hClose h
tryIO $ removeFile tmpfile
use (tmpfile, h) = do
liftIO $ hClose h
a tmpfile content
liftIO $ rename tmpfile file
{- Runs an action with a tmp file located in the system's tmp directory
- (or in "." if there is none) then removes the file. -}
withTmpFile :: (MonadIO m, MonadMask m) => Template -> (FilePath -> Handle -> m a) -> m a
withTmpFile template a = do
tmpdir <- liftIO $ catchDefaultIO "." getTemporaryDirectory
withTmpFileIn tmpdir template a
{- Runs an action with a tmp file located in the specified directory,
- then removes the file. -}
withTmpFileIn :: (MonadIO m, MonadMask m) => FilePath -> Template -> (FilePath -> Handle -> m a) -> m a
withTmpFileIn tmpdir template a = bracket create remove use
where
create = liftIO $ openTempFile tmpdir template
remove (name, h) = liftIO $ do
hClose h
catchBoolIO (removeFile name >> return True)
use (name, h) = a name h
{- Runs an action with a tmp directory located within the system's tmp
- directory (or within "." if there is none), then removes the tmp
- directory and all its contents. -}
withTmpDir :: (MonadMask m, MonadIO m) => Template -> (FilePath -> m a) -> m a
withTmpDir template a = do
topleveltmpdir <- liftIO $ catchDefaultIO "." getTemporaryDirectory
#ifndef mingw32_HOST_OS
-- Use mkdtemp to create a temp directory securely in /tmp.
bracket
(liftIO $ mkdtemp $ topleveltmpdir </> template)
removeTmpDir
a
#else
withTmpDirIn topleveltmpdir template a
#endif
{- Runs an action with a tmp directory located within a specified directory,
- then removes the tmp directory and all its contents. -}
withTmpDirIn :: (MonadMask m, MonadIO m) => FilePath -> Template -> (FilePath -> m a) -> m a
withTmpDirIn tmpdir template = bracketIO create removeTmpDir
where
create = do
createDirectoryIfMissing True tmpdir
makenewdir (tmpdir </> template) (0 :: Int)
makenewdir t n = do
let dir = t ++ "." ++ show n
catchIOErrorType AlreadyExists (const $ makenewdir t $ n + 1) $ do
createDirectory dir
return dir
{- Deletes the entire contents of the the temporary directory, if it
- exists. -}
removeTmpDir :: MonadIO m => FilePath -> m ()
removeTmpDir tmpdir = liftIO $ whenM (doesDirectoryExist tmpdir) $ do
#if mingw32_HOST_OS
-- Windows will often refuse to delete a file
-- after a process has just written to it and exited.
-- Because it's crap, presumably. So, ignore failure
-- to delete the temp directory.
_ <- tryIO $ removeDirectoryRecursive tmpdir
return ()
#else
removeDirectoryRecursive tmpdir
#endif
{- It's not safe to use a FilePath of an existing file as the template
- for openTempFile, because if the FilePath is really long, the tmpfile
- will be longer, and may exceed the maximum filename length.
-
- This generates a template that is never too long.
- (Well, it allocates 20 characters for use in making a unique temp file,
- anyway, which is enough for the current implementation and any
- likely implementation.)
-}
relatedTemplate :: FilePath -> FilePath
relatedTemplate f
| len > 20 = truncateFilePath (len - 20) f
| otherwise = f
where
len = length f