{-# LANGUAGE CPP, ForeignFunctionInterface #-}

module Darcs.Util.Compat
    ( stdoutIsAPipe
    , canonFilename
    , maybeRelink
    , atomicCreate
    , sloppyAtomicCreate
    ) where

import Darcs.Prelude

import Darcs.Util.File ( withCurrentDirectory )

import Control.Monad ( unless )
import Foreign.C.Types ( CInt(..) )
import Foreign.C.String ( CString, withCString )
import Foreign.C.Error ( throwErrno, eEXIST, getErrno )
import System.Directory ( getCurrentDirectory )
import System.IO.Error ( mkIOError, alreadyExistsErrorType )
import System.Posix.Files ( stdFileMode )
import System.Posix.IO ( openFd, closeFd,
                         defaultFileFlags, exclusive,
                         OpenMode(WriteOnly) )

import Darcs.Util.SignalHandler ( stdoutIsAPipe )

canonFilename :: FilePath -> IO FilePath
canonFilename :: [Char] -> IO [Char]
canonFilename f :: [Char]
f@(Char
_:Char
':':[Char]
_) = forall (m :: * -> *) a. Monad m => a -> m a
return [Char]
f -- absolute windows paths
canonFilename f :: [Char]
f@(Char
'/':[Char]
_) = forall (m :: * -> *) a. Monad m => a -> m a
return [Char]
f
canonFilename (Char
'.':Char
'/':[Char]
f) = do [Char]
cd <- IO [Char]
getCurrentDirectory
                               forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ [Char]
cd forall a. [a] -> [a] -> [a]
++ [Char]
"/" forall a. [a] -> [a] -> [a]
++ [Char]
f
canonFilename [Char]
f = case forall a. [a] -> [a]
reverse forall a b. (a -> b) -> a -> b
$ forall a. (a -> Bool) -> [a] -> [a]
dropWhile (forall a. Eq a => a -> a -> Bool
/=Char
'/') forall a b. (a -> b) -> a -> b
$ forall a. [a] -> [a]
reverse [Char]
f of
                  [Char]
"" -> forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (forall a. [a] -> [a] -> [a]
++(Char
'/'forall a. a -> [a] -> [a]
:[Char]
f)) IO [Char]
getCurrentDirectory
                  [Char]
rd -> forall p a. FilePathLike p => p -> IO a -> IO a
withCurrentDirectory [Char]
rd forall a b. (a -> b) -> a -> b
$
                          do [Char]
fd <- IO [Char]
getCurrentDirectory
                             forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ [Char]
fd forall a. [a] -> [a] -> [a]
++ [Char]
"/" forall a. [a] -> [a] -> [a]
++ [Char]
simplefilename
    where
    simplefilename :: [Char]
simplefilename = forall a. [a] -> [a]
reverse forall a b. (a -> b) -> a -> b
$ forall a. (a -> Bool) -> [a] -> [a]
takeWhile (forall a. Eq a => a -> a -> Bool
/=Char
'/') forall a b. (a -> b) -> a -> b
$ forall a. [a] -> [a]
reverse [Char]
f


foreign import ccall unsafe "maybe_relink.h maybe_relink" maybe_relink
    :: CString -> CString -> CInt -> IO CInt

-- Checks whether src and dst are identical.  If so, makes dst into a
-- link to src.  Returns True if dst is a link to src (either because
-- we linked it or it already was).  Safe against changes to src if
-- they are not in place, but not to dst.
maybeRelink :: String -> String -> IO Bool
maybeRelink :: [Char] -> [Char] -> IO Bool
maybeRelink [Char]
src [Char]
dst =
    forall a. [Char] -> (CString -> IO a) -> IO a
withCString [Char]
src forall a b. (a -> b) -> a -> b
$ \CString
csrc ->
    forall a. [Char] -> (CString -> IO a) -> IO a
withCString [Char]
dst forall a b. (a -> b) -> a -> b
$ \CString
cdst ->
    do CInt
rc <- CString -> CString -> CInt -> IO CInt
maybe_relink CString
csrc CString
cdst CInt
1
       case CInt
rc of
        CInt
0 -> forall (m :: * -> *) a. Monad m => a -> m a
return Bool
True
        CInt
1 -> forall (m :: * -> *) a. Monad m => a -> m a
return Bool
True
        -1 -> forall a. [Char] -> IO a
throwErrno ([Char]
"Relinking " forall a. [a] -> [a] -> [a]
++ [Char]
dst)
        -2 -> forall (m :: * -> *) a. Monad m => a -> m a
return Bool
False
        -3 -> do [Char] -> IO ()
putStrLn ([Char]
"Relinking: race condition avoided on file " forall a. [a] -> [a] -> [a]
++
                            [Char]
dst)
                 forall (m :: * -> *) a. Monad m => a -> m a
return Bool
False
        CInt
_ -> forall (m :: * -> *) a. MonadFail m => [Char] -> m a
fail ([Char]
"Unexpected situation when relinking " forall a. [a] -> [a] -> [a]
++ [Char]
dst)

sloppyAtomicCreate :: FilePath -> IO ()
sloppyAtomicCreate :: [Char] -> IO ()
sloppyAtomicCreate [Char]
fp
    = do Fd
fd <- [Char] -> OpenMode -> Maybe FileMode -> OpenFileFlags -> IO Fd
openFd [Char]
fp OpenMode
WriteOnly (forall a. a -> Maybe a
Just FileMode
stdFileMode) OpenFileFlags
flags
         Fd -> IO ()
closeFd Fd
fd
  where flags :: OpenFileFlags
flags = OpenFileFlags
defaultFileFlags { exclusive :: Bool
exclusive = Bool
True }

atomicCreate :: FilePath -> IO ()
atomicCreate :: [Char] -> IO ()
atomicCreate [Char]
fp = forall a. [Char] -> (CString -> IO a) -> IO a
withCString [Char]
fp forall a b. (a -> b) -> a -> b
$ \CString
cstr -> do
    CInt
rc <- CString -> IO CInt
c_atomic_create CString
cstr
    forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (CInt
rc forall a. Ord a => a -> a -> Bool
>= CInt
0) forall a b. (a -> b) -> a -> b
$
           do Errno
errno <- IO Errno
getErrno
              [Char]
pwd <- IO [Char]
getCurrentDirectory
              if Errno
errno forall a. Eq a => a -> a -> Bool
== Errno
eEXIST
                 then forall a. IOError -> IO a
ioError forall a b. (a -> b) -> a -> b
$ IOErrorType -> [Char] -> Maybe Handle -> Maybe [Char] -> IOError
mkIOError IOErrorType
alreadyExistsErrorType
                                          ([Char]
"atomicCreate in "forall a. [a] -> [a] -> [a]
++[Char]
pwd)
                                          forall a. Maybe a
Nothing (forall a. a -> Maybe a
Just [Char]
fp)
                 else forall a. [Char] -> IO a
throwErrno forall a b. (a -> b) -> a -> b
$ [Char]
"atomicCreate "forall a. [a] -> [a] -> [a]
++[Char]
fpforall a. [a] -> [a] -> [a]
++[Char]
" in "forall a. [a] -> [a] -> [a]
++[Char]
pwd

foreign import ccall unsafe "atomic_create.h atomic_create" c_atomic_create
    :: CString -> IO CInt