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