Windows: Work around win32 length limits when dealing with lock files
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3 changed files with 69 additions and 2 deletions
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@ -1,10 +1,12 @@
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{- Windows lock files
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-
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- Copyright 2014 Joey Hess <id@joeyh.name>
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- Copyright 2014,2021 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 OverloadedStrings #-}
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module Utility.LockFile.Windows (
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lockShared,
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lockExclusive,
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@ -16,8 +18,12 @@ module Utility.LockFile.Windows (
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import System.Win32.Types
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import System.Win32.File
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import Control.Concurrent
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import qualified Data.ByteString as B
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import qualified System.FilePath.Windows.ByteString as P
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import Utility.FileSystemEncoding
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import Utility.Split
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import Utility.Path.AbsRel
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type LockFile = RawFilePath
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@ -53,7 +59,8 @@ lockExclusive = openLock fILE_SHARE_NONE
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-}
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openLock :: ShareMode -> LockFile -> IO (Maybe LockHandle)
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openLock sharemode f = do
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h <- withTString (fromRawFilePath f) $ \c_f ->
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f' <- convertToNativeNamespace f
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h <- withTString (fromRawFilePath f') $ \c_f ->
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c_CreateFile c_f gENERIC_READ sharemode security_attributes
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oPEN_ALWAYS fILE_ATTRIBUTE_NORMAL (maybePtr Nothing)
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return $ if h == iNVALID_HANDLE_VALUE
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@ -62,6 +69,32 @@ openLock sharemode f = do
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where
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security_attributes = maybePtr Nothing
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{- Convert a filepath to use Windows's native namespace.
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- This avoids filesystem length limits.
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-
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- This is similar to the way base converts filenames on windows,
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- but as that is implemented in C (create_device_name) and not
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- exported, it cannot be used here. Several edge cases are not handled,
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- including network shares and dos short paths.
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-}
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convertToNativeNamespace :: RawFilePath -> IO RawFilePath
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convertToNativeNamespace f
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| win32_dev_namespace `B.isPrefixOf` f = return f
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| win32_file_namespace `B.isPrefixOf` f = return f
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| nt_device_namespace `B.isPrefixOf` f = return f
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| otherwise = do
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-- Make absolute because any '.' and '..' in the path
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-- will not be resolved once it's converted.
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p <- absPath f
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-- Normalize slashes.
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let p' = P.normalise p
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return (win32_file_namespace <> p')
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where
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win32_dev_namespace = "\\\\.\\"
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win32_file_namespace = "\\\\?\\"
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nt_device_namespace = "\\Device\\"
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dropLock :: LockHandle -> IO ()
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dropLock = closeHandle
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