git-annex/Utility/Tmp.hs
Joey Hess 54ad1b4cfb
Windows: Support long filenames in more (possibly all) of the code
Works around this bug in unix-compat:
https://github.com/jacobstanley/unix-compat/issues/56
getFileStatus and other FilePath using functions in unix-compat do not do
UNC conversion on Windows.

Made Utility.RawFilePath use convertToWindowsNativeNamespace to do the
necessary conversion on windows to support long filenames.

Audited all imports of System.PosixCompat.Files to make sure that no
functions that operate on FilePath were imported from it. Instead, use
the equvilants from Utility.RawFilePath. In particular the
re-export of that module in Common had to be removed, which led to lots
of other changes throughout the code.

The changes to Build.Configure, Build.DesktopFile, and Build.TestConfig
make Utility.Directory not be needed to build setup. And so let it use
Utility.RawFilePath, which depends on unix, which cannot be in
setup-depends.

Sponsored-by: Dartmouth College's Datalad project
2023-03-01 15:55:58 -04:00

111 lines
3.5 KiB
Haskell

{- Temporary files.
-
- Copyright 2010-2020 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# LANGUAGE CPP #-}
{-# OPTIONS_GHC -fno-warn-tabs #-}
module Utility.Tmp (
Template,
viaTmp,
withTmpFile,
withTmpFileIn,
relatedTemplate,
openTmpFileIn,
) where
import System.IO
import System.FilePath
import System.Directory
import Control.Monad.IO.Class
import System.IO.Error
import Utility.Exception
import Utility.FileSystemEncoding
import Utility.FileMode
import qualified Utility.RawFilePath as R
type Template = String
{- This is the same as openTempFile, except when there is an
- error, it displays the template as well as the directory,
- to help identify what call was responsible.
-}
openTmpFileIn :: FilePath -> String -> IO (FilePath, Handle)
openTmpFileIn dir template = openTempFile dir template
`catchIO` decoraterrror
where
decoraterrror e = throwM $
let loc = ioeGetLocation e ++ " template " ++ template
in annotateIOError e loc Nothing Nothing
{- 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.
-
- While this uses a temp file, the file will end up with the same
- mode as it would when using writeFile, unless the writer action changes
- it.
-}
viaTmp :: (MonadMask m, MonadIO m) => (FilePath -> v -> m ()) -> FilePath -> v -> m ()
viaTmp a file content = bracketIO setup cleanup use
where
(dir, base) = splitFileName file
template = relatedTemplate (base ++ ".tmp")
setup = do
createDirectoryIfMissing True dir
openTmpFileIn dir template
cleanup (tmpfile, h) = do
_ <- tryIO $ hClose h
tryIO $ removeFile tmpfile
use (tmpfile, h) = do
let tmpfile' = toRawFilePath tmpfile
-- Make mode the same as if the file were created usually,
-- not as a temp file. (This may fail on some filesystems
-- that don't support file modes well, so ignore
-- exceptions.)
_ <- liftIO $ tryIO $ R.setFileMode tmpfile' =<< defaultFileMode
liftIO $ hClose h
a tmpfile content
liftIO $ R.rename tmpfile' (toRawFilePath 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.
-
- Note that the tmp file will have a file mode that only allows the
- current user to access it.
-}
withTmpFileIn :: (MonadIO m, MonadMask m) => FilePath -> Template -> (FilePath -> Handle -> m a) -> m a
withTmpFileIn tmpdir template a = bracket create remove use
where
create = liftIO $ openTmpFileIn tmpdir template
remove (name, h) = liftIO $ do
hClose h
catchBoolIO (removeFile name >> return True)
use (name, h) = a name h
{- 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