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{-# LANGUAGE ForeignFunctionInterface, CPP #-}
module Distribution.Client.Utils ( MergeResult(..)
, mergeBy, duplicates, duplicatesBy
, inDir, determineNumJobs, numberOfProcessors
, removeExistingFile
, makeAbsoluteToCwd, filePathToByteString
, byteStringToFilePath, tryCanonicalizePath
, canonicalizePathNoThrow
, moreRecentFile, existsAndIsMoreRecentThan )
where
import Distribution.Compat.Exception ( catchIO )
import Distribution.Client.Compat.Time ( getModTime )
import Distribution.Simple.Setup ( Flag(..) )
import qualified Data.ByteString.Lazy as BS
import Control.Monad
( when )
import Data.Bits
( (.|.), shiftL, shiftR )
import Data.Char
( ord, chr )
import Data.List
( sortBy, groupBy )
import Data.Word
( Word8, Word32)
import Foreign.C.Types ( CInt(..) )
import qualified Control.Exception as Exception
( finally )
import System.Directory
( canonicalizePath, doesFileExist, getCurrentDirectory
, removeFile, setCurrentDirectory )
import System.FilePath
( (</>), isAbsolute )
import System.IO.Unsafe ( unsafePerformIO )
#if defined(mingw32_HOST_OS)
import Prelude hiding (ioError)
import Control.Monad (liftM2, unless)
import System.Directory (doesDirectoryExist)
import System.IO.Error (ioError, mkIOError, doesNotExistErrorType)
#endif
-- | Generic merging utility. For sorted input lists this is a full outer join.
--
-- * The result list never contains @(Nothing, Nothing)@.
--
mergeBy :: (a -> b -> Ordering) -> [a] -> [b] -> [MergeResult a b]
mergeBy cmp = merge
where
merge [] ys = [ OnlyInRight y | y <- ys]
merge xs [] = [ OnlyInLeft x | x <- xs]
merge (x:xs) (y:ys) =
case x `cmp` y of
GT -> OnlyInRight y : merge (x:xs) ys
EQ -> InBoth x y : merge xs ys
LT -> OnlyInLeft x : merge xs (y:ys)
data MergeResult a b = OnlyInLeft a | InBoth a b | OnlyInRight b
duplicates :: Ord a => [a] -> [[a]]
duplicates = duplicatesBy compare
duplicatesBy :: (a -> a -> Ordering) -> [a] -> [[a]]
duplicatesBy cmp = filter moreThanOne . groupBy eq . sortBy cmp
where
eq a b = case cmp a b of
EQ -> True
_ -> False
moreThanOne (_:_:_) = True
moreThanOne _ = False
-- | Like 'removeFile', but does not throw an exception when the file does not
-- exist.
removeExistingFile :: FilePath -> IO ()
removeExistingFile path = do
exists <- doesFileExist path
when exists $
removeFile path
-- | Executes the action in the specified directory.
inDir :: Maybe FilePath -> IO a -> IO a
inDir Nothing m = m
inDir (Just d) m = do
old <- getCurrentDirectory
setCurrentDirectory d
m `Exception.finally` setCurrentDirectory old
foreign import ccall "getNumberOfProcessors" c_getNumberOfProcessors :: IO CInt
-- The number of processors is not going to change during the duration of the
-- program, so unsafePerformIO is safe here.
numberOfProcessors :: Int
numberOfProcessors = fromEnum $ unsafePerformIO c_getNumberOfProcessors
-- | Determine the number of jobs to use given the value of the '-j' flag.
determineNumJobs :: Flag (Maybe Int) -> Int
determineNumJobs numJobsFlag =
case numJobsFlag of
NoFlag -> 1
Flag Nothing -> numberOfProcessors
Flag (Just n) -> n
-- | Given a relative path, make it absolute relative to the current
-- directory. Absolute paths are returned unmodified.
makeAbsoluteToCwd :: FilePath -> IO FilePath
makeAbsoluteToCwd path | isAbsolute path = return path
| otherwise = do cwd <- getCurrentDirectory
return $! cwd </> path
-- | Convert a 'FilePath' to a lazy 'ByteString'. Each 'Char' is
-- encoded as a little-endian 'Word32'.
filePathToByteString :: FilePath -> BS.ByteString
filePathToByteString p =
BS.pack $ foldr conv [] codepts
where
codepts :: [Word32]
codepts = map (fromIntegral . ord) p
conv :: Word32 -> [Word8] -> [Word8]
conv w32 rest = b0:b1:b2:b3:rest
where
b0 = fromIntegral $ w32
b1 = fromIntegral $ w32 `shiftR` 8
b2 = fromIntegral $ w32 `shiftR` 16
b3 = fromIntegral $ w32 `shiftR` 24
-- | Reverse operation to 'filePathToByteString'.
byteStringToFilePath :: BS.ByteString -> FilePath
byteStringToFilePath bs | bslen `mod` 4 /= 0 = unexpected
| otherwise = go 0
where
unexpected = "Distribution.Client.Utils.byteStringToFilePath: unexpected"
bslen = BS.length bs
go i | i == bslen = []
| otherwise = (chr . fromIntegral $ w32) : go (i+4)
where
w32 :: Word32
w32 = b0 .|. (b1 `shiftL` 8) .|. (b2 `shiftL` 16) .|. (b3 `shiftL` 24)
b0 = fromIntegral $ BS.index bs i
b1 = fromIntegral $ BS.index bs (i + 1)
b2 = fromIntegral $ BS.index bs (i + 2)
b3 = fromIntegral $ BS.index bs (i + 3)
-- | Workaround for the inconsistent behaviour of 'canonicalizePath'. It throws
-- an error if the path refers to a non-existent file on *nix, but not on
-- Windows.
tryCanonicalizePath :: FilePath -> IO FilePath
tryCanonicalizePath path = do
ret <- canonicalizePath path
#if defined(mingw32_HOST_OS)
exists <- liftM2 (||) (doesFileExist ret) (doesDirectoryExist ret)
unless exists $
ioError $ mkIOError doesNotExistErrorType "canonicalizePath"
Nothing (Just ret)
#endif
return ret
-- | A non-throwing wrapper for 'canonicalizePath'. If 'canonicalizePath' throws
-- an exception, returns the path argument unmodified.
canonicalizePathNoThrow :: FilePath -> IO FilePath
canonicalizePathNoThrow path = do
canonicalizePath path `catchIO` (\_ -> return path)
--------------------
-- Modification time
-- | Like Distribution.Simple.Utils.moreRecentFile, but uses getModTime instead
-- of getModificationTime for higher precision. We can't merge the two because
-- Distribution.Client.Time uses MIN_VERSION macros.
moreRecentFile :: FilePath -> FilePath -> IO Bool
moreRecentFile a b = do
exists <- doesFileExist b
if not exists
then return True
else do tb <- getModTime b
ta <- getModTime a
return (ta > tb)
-- | Like 'moreRecentFile', but also checks that the first file exists.
existsAndIsMoreRecentThan :: FilePath -> FilePath -> IO Bool
existsAndIsMoreRecentThan a b = do
exists <- doesFileExist a
if not exists
then return False
else a `moreRecentFile` b
|
