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