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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 (
ShellParam(..),
toShell,
hGetContentsStrict,
readFileStrict,
parentDir,
absPath,
relPathCwdToDir,
relPathDirToDir,
boolSystem,
shellEscape,
shellUnEscape,
unsetFileMode,
readMaybe,
safeWriteFile,
dirContains,
prop_idempotent_shellEscape,
prop_idempotent_shellEscape_multiword,
prop_parentDir_basics,
prop_relPathDirToDir_basics
) 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)
import Data.List
import Control.Monad (liftM2)
{- A type for parameters passed to a shell command. A command can
- be passed either some Params (multiple parameters can be included,
- whitespace-separated, or a single Param (for when parameters contain
- whitespace), or a File.
-}
data ShellParam = Params String | Param String | File FilePath
deriving (Eq, Show, Ord)
{- When converting ShellParam to a String in preparation for passing to
- a shell command, Files that start with a dash are modified to avoid
- the shell command interpreting them as options. -}
toShell :: [ShellParam] -> [String]
toShell l = concat $ map unwrap l
where
unwrap (Param s) = [s]
unwrap (Params s) = filter (not . null) (split " " s)
unwrap (File ('-':s)) = ["./-" ++ s]
unwrap (File (s)) = [s]
{- 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 -> [ShellParam] -> 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 (toShell 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
{- Unescapes a set of shellEscaped words or filenames. -}
shellUnEscape :: String -> [String]
shellUnEscape [] = []
shellUnEscape s = word:(shellUnEscape rest)
where
(word, rest) = findword "" s
findword w [] = (w, "")
findword w (c:cs)
| c == ' ' = (w, cs)
| c == '\'' = inquote c w cs
| c == '"' = inquote c w cs
| otherwise = findword (w++[c]) cs
inquote _ w [] = (w, "")
inquote q w (c:cs)
| c == q = findword w cs
| otherwise = inquote q (w++[c]) cs
{- For quickcheck. -}
prop_idempotent_shellEscape :: String -> Bool
prop_idempotent_shellEscape s = [s] == (shellUnEscape $ shellEscape s)
prop_idempotent_shellEscape_multiword :: [String] -> Bool
prop_idempotent_shellEscape_multiword s = s == (shellUnEscape $ unwords $ map shellEscape s)
{- 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
{- A version of readFile that is not lazy. -}
readFileStrict :: FilePath -> IO String
readFileStrict f = readFile f >>= \s -> length s `seq` return s
{- Returns the parent directory of a path. Parent of / is "" -}
parentDir :: FilePath -> FilePath
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]
prop_parentDir_basics :: FilePath -> Bool
prop_parentDir_basics dir
| null dir = True
| dir == "/" = parentDir dir == ""
| otherwise = p /= dir
where
p = parentDir dir
{- Checks if the first FilePath is, or could be said to contain the second.
- For example, "foo/" contains "foo/bar". Also, "foo", "./foo", "foo/" etc
- are all equivilant.
-}
dirContains :: FilePath -> FilePath -> Bool
dirContains a b = a == b || a' == b' || (a'++"/") `isPrefixOf` b'
where
norm p = case (absNormPath p ".") of
Just r -> r
Nothing -> ""
a' = norm a
b' = norm b
{- 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 = liftM2 relPathDirToDir getCurrentDirectory (absPath dir)
{- 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
prop_relPathDirToDir_basics :: FilePath -> FilePath -> Bool
prop_relPathDirToDir_basics from to
| from == to = null r
| otherwise = not (null r) && (last r == '/')
where
r = relPathDirToDir from to
{- 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
{- Writes a file using a temp file that is renamed atomically into place. -}
safeWriteFile :: FilePath -> String -> IO ()
safeWriteFile file content = do
pid <- getProcessID
let tmpfile = file ++ ".tmp" ++ show pid
createDirectoryIfMissing True (parentDir file)
writeFile tmpfile content
renameFile tmpfile file
|
