141 lines
4 KiB
Haskell
141 lines
4 KiB
Haskell
{- git-annex utility functions
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-
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- Copyright 2010 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Utility (
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hGetContentsStrict,
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readFileStrict,
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parentDir,
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absPath,
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relPathCwdToDir,
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relPathDirToDir,
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boolSystem,
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shellEscape,
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unsetFileMode,
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readMaybe
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) where
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import System.IO
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import System.Exit
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import System.Posix.Process
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import System.Posix.Signals
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import System.Posix.Files
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import System.Posix.Types
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import Data.String.Utils
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import System.Path
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import System.FilePath
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import System.Directory
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import Foreign (complement)
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{- A version of hgetContents that is not lazy. Ensures file is
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- all read before it gets closed. -}
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hGetContentsStrict :: Handle -> IO String
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hGetContentsStrict h = hGetContents h >>= \s -> length s `seq` return s
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{- A version of readFile that is not lazy. -}
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readFileStrict :: FilePath -> IO String
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readFileStrict f = readFile f >>= \s -> length s `seq` return s
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{- Returns the parent directory of a path. Parent of / is "" -}
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parentDir :: String -> String
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parentDir dir =
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if not $ null dirs
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then slash ++ join s (take (length dirs - 1) dirs)
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else ""
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where
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dirs = filter (not . null) $ split s dir
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slash = if isAbsolute dir then s else ""
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s = [pathSeparator]
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{- Converts a filename into a normalized, absolute path. -}
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absPath :: FilePath -> IO FilePath
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absPath file = do
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cwd <- getCurrentDirectory
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case absNormPath cwd file of
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Just f -> return f
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Nothing -> error $ "unable to normalize " ++ file
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{- Constructs a relative path from the CWD to a directory.
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-
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- For example, assuming CWD is /tmp/foo/bar:
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- relPathCwdToDir "/tmp/foo" == "../"
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- relPathCwdToDir "/tmp/foo/bar" == ""
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-}
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relPathCwdToDir :: FilePath -> IO FilePath
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relPathCwdToDir dir = do
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cwd <- getCurrentDirectory
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a <- absPath dir
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return $ relPathDirToDir cwd a
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{- Constructs a relative path from one directory to another.
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-
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- Both directories must be absolute, and normalized (eg with absNormpath).
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-
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- The path will end with "/", unless it is empty.
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-}
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relPathDirToDir :: FilePath -> FilePath -> FilePath
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relPathDirToDir from to =
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if not $ null path
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then addTrailingPathSeparator path
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else ""
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where
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s = [pathSeparator]
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pfrom = split s from
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pto = split s to
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common = map fst $ filter same $ zip pfrom pto
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same (c,d) = c == d
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uncommon = drop numcommon pto
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dotdots = replicate (length pfrom - numcommon) ".."
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numcommon = length common
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path = join s $ dotdots ++ uncommon
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{- Run a system command, and returns True or False
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- if it succeeded or failed.
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-
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- SIGINT(ctrl-c) is allowed to propigate and will terminate the program.
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-}
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boolSystem :: FilePath -> [String] -> IO Bool
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boolSystem command params = do
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-- Going low-level because all the high-level system functions
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-- block SIGINT etc. We need to block SIGCHLD, but allow
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-- SIGINT to do its default program termination.
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let sigset = addSignal sigCHLD emptySignalSet
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oldint <- installHandler sigINT Default Nothing
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oldset <- getSignalMask
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blockSignals sigset
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childpid <- forkProcess $ childaction oldint oldset
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mps <- getProcessStatus True False childpid
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restoresignals oldint oldset
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case mps of
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Just (Exited ExitSuccess) -> return True
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_ -> return False
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where
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restoresignals oldint oldset = do
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_ <- installHandler sigINT oldint Nothing
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setSignalMask oldset
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childaction oldint oldset = do
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restoresignals oldint oldset
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executeFile command True params Nothing
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{- Escapes a filename to be safely able to be exposed to the shell. -}
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shellEscape :: FilePath -> String
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shellEscape f = "'" ++ escaped ++ "'"
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where
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-- replace ' with '"'"'
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escaped = join "'\"'\"'" $ split "'" f
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{- Removes a FileMode from a file.
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- For example, call with otherWriteMode to chmod o-w -}
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unsetFileMode :: FilePath -> FileMode -> IO ()
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unsetFileMode f m = do
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s <- getFileStatus f
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setFileMode f $ fileMode s `intersectFileModes` complement m
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{- Attempts to read a value from a String. -}
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readMaybe :: (Read a) => String -> Maybe a
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readMaybe s = case reads s of
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((x,_):_) -> Just x
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_ -> Nothing
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