{-# LINE 1 "libraries/unix/System/Posix/IO/Common.hsc" #-}
{-# LANGUAGE CApiFFI #-}
{-# LANGUAGE NondecreasingIndentation #-}
{-# LANGUAGE RecordWildCards #-}

{-# LINE 5 "libraries/unix/System/Posix/IO/Common.hsc" #-}
{-# LANGUAGE Safe #-}

{-# LINE 9 "libraries/unix/System/Posix/IO/Common.hsc" #-}

-----------------------------------------------------------------------------
-- |
-- Module      :  System.Posix.IO.Common
-- Copyright   :  (c) The University of Glasgow 2002
-- License     :  BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer  :  libraries@haskell.org
-- Stability   :  provisional
-- Portability :  non-portable (requires POSIX)
--
-----------------------------------------------------------------------------

module System.Posix.IO.Common (
    -- * Input \/ Output

    -- ** Standard file descriptors
    stdInput, stdOutput, stdError,

    -- ** Opening and closing files
    OpenMode(..),
    OpenFileFlags(..), defaultFileFlags,
    open_,
    closeFd,

    -- ** Reading\/writing data
    -- |Programmers using the 'fdRead' and 'fdWrite' API should be aware that
    -- EAGAIN exceptions may occur for non-blocking IO!

    fdRead, fdWrite,
    fdReadBuf, fdWriteBuf,

    -- ** Seeking
    fdSeek,

    -- ** File options
    FdOption(..),
    queryFdOption,
    setFdOption,

    -- ** Locking
    FileLock,
    LockRequest(..),
    getLock,  setLock,
    waitToSetLock,

    -- ** Pipes
    createPipe,

    -- ** Duplicating file descriptors
    dup, dupTo,

    -- ** Converting file descriptors to\/from Handles
    handleToFd,
    fdToHandle,

  ) where

import System.IO
import System.IO.Error
import System.Posix.Types
import qualified System.Posix.Internals as Base

import Foreign
import Foreign.C

import GHC.IO.Handle.Internals
import GHC.IO.Handle.Types
import qualified GHC.IO.FD as FD
import qualified GHC.IO.Handle.FD as FD
import GHC.IO.Exception
import Data.Typeable (cast)



-- -----------------------------------------------------------------------------
-- Pipes
-- |The 'createPipe' function creates a pair of connected file
-- descriptors. The first component is the fd to read from, the second
-- is the write end.  Although pipes may be bidirectional, this
-- behaviour is not portable and programmers should use two separate
-- pipes for this purpose.  May throw an exception if this is an
-- invalid descriptor.

createPipe :: IO (Fd, Fd)
createPipe =
  allocaArray 2 $ \p_fd -> do
    throwErrnoIfMinus1_ "createPipe" (c_pipe p_fd)
    rfd <- peekElemOff p_fd 0
    wfd <- peekElemOff p_fd 1
    return (Fd rfd, Fd wfd)

foreign import ccall unsafe "pipe"
   c_pipe :: Ptr CInt -> IO CInt

-- -----------------------------------------------------------------------------
-- Duplicating file descriptors

-- | May throw an exception if this is an invalid descriptor.
dup :: Fd -> IO Fd
dup (Fd fd) = do r <- throwErrnoIfMinus1 "dup" (c_dup fd); return (Fd r)

-- | May throw an exception if this is an invalid descriptor.
dupTo :: Fd -> Fd -> IO Fd
dupTo (Fd fd1) (Fd fd2) = do
  r <- throwErrnoIfMinus1 "dupTo" (c_dup2 fd1 fd2)
  return (Fd r)

foreign import ccall unsafe "dup"
   c_dup :: CInt -> IO CInt

foreign import ccall unsafe "dup2"
   c_dup2 :: CInt -> CInt -> IO CInt

-- -----------------------------------------------------------------------------
-- Opening and closing files

stdInput, stdOutput, stdError :: Fd
stdInput   = Fd (0)
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stdOutput  = Fd (1)
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stdError   = Fd (2)
{-# LINE 130 "libraries/unix/System/Posix/IO/Common.hsc" #-}

data OpenMode = ReadOnly | WriteOnly | ReadWrite

-- |Correspond to some of the int flags from C's fcntl.h.
data OpenFileFlags =
 OpenFileFlags {
    append    :: Bool,           -- ^ O_APPEND
    exclusive :: Bool,           -- ^ O_EXCL
                                 --
                                 -- __NOTE__: Result is undefined if 'creat' is 'Nothing'.
    noctty    :: Bool,           -- ^ O_NOCTTY
    nonBlock  :: Bool,           -- ^ O_NONBLOCK
    trunc     :: Bool,           -- ^ O_TRUNC
    nofollow  :: Bool,           -- ^ O_NOFOLLOW
                                 --
                                 -- @since 2.8.0.0
    creat     :: Maybe FileMode, -- ^ O_CREAT
                                 --
                                 -- @since 2.8.0.0
    cloexec   :: Bool,           -- ^ O_CLOEXEC
                                 --
                                 -- @since 2.8.0.0
    directory :: Bool,           -- ^ O_DIRECTORY
                                 --
                                 -- @since 2.8.0.0
    sync      :: Bool            -- ^ O_SYNC
                                 --
                                 -- @since 2.8.0.0
 }


-- | Default values for the 'OpenFileFlags' type.
--
-- Each field of 'OpenFileFlags' is either 'False' or 'Nothing'
-- respectively.
defaultFileFlags :: OpenFileFlags
defaultFileFlags =
 OpenFileFlags {
    append    = False,
    exclusive = False,
    noctty    = False,
    nonBlock  = False,
    trunc     = False,
    nofollow  = False,
    creat     = Nothing,
    cloexec   = False,
    directory = False,
    sync      = False
  }


-- |Open and optionally create this file.  See 'System.Posix.Files'
-- for information on how to use the 'FileMode' type.
open_  :: CString
       -> OpenMode
       -> OpenFileFlags
       -> IO Fd
open_ str how (OpenFileFlags appendFlag exclusiveFlag nocttyFlag
                                nonBlockFlag truncateFlag nofollowFlag
                                creatFlag cloexecFlag directoryFlag
                                syncFlag) = do
    fd <- c_open str all_flags mode_w
    return (Fd fd)
  where
    all_flags  = creat .|. flags .|. open_mode

    flags =
       (if appendFlag       then (1024)    else 0) .|.
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       (if exclusiveFlag    then (128)      else 0) .|.
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       (if nocttyFlag       then (256)    else 0) .|.
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       (if nonBlockFlag     then (2048)  else 0) .|.
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       (if truncateFlag     then (512)     else 0) .|.
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       (if nofollowFlag     then (131072)  else 0) .|.
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       (if cloexecFlag      then (524288)   else 0) .|.
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       (if directoryFlag    then (65536) else 0) .|.
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       (if syncFlag         then (1052672)      else 0)
{-# LINE 206 "libraries/unix/System/Posix/IO/Common.hsc" #-}

    (creat, mode_w) = case creatFlag of
                        Nothing -> (0,0)
                        Just x  -> ((64), x)
{-# LINE 210 "libraries/unix/System/Posix/IO/Common.hsc" #-}

    open_mode = case how of
                   ReadOnly  -> (0)
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                   WriteOnly -> (1)
{-# LINE 214 "libraries/unix/System/Posix/IO/Common.hsc" #-}
                   ReadWrite -> (2)
{-# LINE 215 "libraries/unix/System/Posix/IO/Common.hsc" #-}

foreign import capi unsafe "HsUnix.h open"
   c_open :: CString -> CInt -> CMode -> IO CInt

-- |Close this file descriptor.  May throw an exception if this is an
-- invalid descriptor.

closeFd :: Fd -> IO ()
closeFd (Fd fd) = throwErrnoIfMinus1_ "closeFd" (c_close fd)
-- Here we don't to retry on EINTR because according to
--  http://pubs.opengroup.org/onlinepubs/9699919799/functions/close.html
-- "with errno set to [EINTR] [...] the state of fildes is unspecified"
-- and on Linux, already the first close() removes the FD from the process's
-- FD table so closing a second time is invalid
-- (see http://man7.org/linux/man-pages/man2/close.2.html#NOTES).

foreign import ccall unsafe "HsUnix.h close"
   c_close :: CInt -> IO CInt

-- -----------------------------------------------------------------------------
-- Converting file descriptors to/from Handles

-- | Extracts the 'Fd' from a 'Handle'.  This function has the side effect
-- of closing the 'Handle' and flushing its write buffer, if necessary.
handleToFd :: Handle -> IO Fd

-- | Converts an 'Fd' into a 'Handle' that can be used with the
-- standard Haskell IO library (see "System.IO").
fdToHandle :: Fd -> IO Handle
fdToHandle fd = FD.fdToHandle (fromIntegral fd)

handleToFd h@(FileHandle _ m) = do
  withHandle' "handleToFd" h m $ handleToFd' h
handleToFd h@(DuplexHandle _ r w) = do
  _ <- withHandle' "handleToFd" h r $ handleToFd' h
  withHandle' "handleToFd" h w $ handleToFd' h
  -- for a DuplexHandle, make sure we mark both sides as closed,
  -- otherwise a finalizer will come along later and close the other
  -- side. (#3914)

handleToFd' :: Handle -> Handle__ -> IO (Handle__, Fd)
handleToFd' h h_@Handle__{haType=_,..} = do
  case cast haDevice of
    Nothing -> ioError (ioeSetErrorString (mkIOError IllegalOperation
                                           "handleToFd" (Just h) Nothing)
                        "handle is not a file descriptor")
    Just fd -> do
     -- converting a Handle into an Fd effectively means
     -- letting go of the Handle; it is put into a closed
     -- state as a result.
     flushWriteBuffer h_
     FD.release fd
     return (Handle__{haType=ClosedHandle,..}, Fd (FD.fdFD fd))


-- -----------------------------------------------------------------------------
-- Fd options

data FdOption = AppendOnWrite     -- ^O_APPEND
              | CloseOnExec       -- ^FD_CLOEXEC
              | NonBlockingRead   -- ^O_NONBLOCK
              | SynchronousWrites -- ^O_SYNC

fdOption2Int :: FdOption -> CInt
fdOption2Int CloseOnExec       = (1)
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fdOption2Int AppendOnWrite     = (1024)
{-# LINE 281 "libraries/unix/System/Posix/IO/Common.hsc" #-}
fdOption2Int NonBlockingRead   = (2048)
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fdOption2Int SynchronousWrites = (1052672)
{-# LINE 283 "libraries/unix/System/Posix/IO/Common.hsc" #-}

-- | May throw an exception if this is an invalid descriptor.
queryFdOption :: Fd -> FdOption -> IO Bool
queryFdOption (Fd fd) opt = do
  r <- throwErrnoIfMinus1 "queryFdOption" (Base.c_fcntl_read fd flag)
  return ((r .&. fdOption2Int opt) /= 0)
 where
  flag    = case opt of
              CloseOnExec       -> (1)
{-# LINE 292 "libraries/unix/System/Posix/IO/Common.hsc" #-}
              _                 -> (3)
{-# LINE 293 "libraries/unix/System/Posix/IO/Common.hsc" #-}

-- | May throw an exception if this is an invalid descriptor.
setFdOption :: Fd -> FdOption -> Bool -> IO ()
setFdOption (Fd fd) opt val = do
  r <- throwErrnoIfMinus1 "setFdOption" (Base.c_fcntl_read fd getflag)
  let r' | val       = r .|. opt_val
         | otherwise = r .&. (complement opt_val)
  throwErrnoIfMinus1_ "setFdOption"
                      (Base.c_fcntl_write fd setflag (fromIntegral r'))
 where
  (getflag,setflag)= case opt of
              CloseOnExec       -> ((1),(2))
{-# LINE 305 "libraries/unix/System/Posix/IO/Common.hsc" #-}
              _                 -> ((3),(4))
{-# LINE 306 "libraries/unix/System/Posix/IO/Common.hsc" #-}
  opt_val = fdOption2Int opt

-- -----------------------------------------------------------------------------
-- Seeking

mode2Int :: SeekMode -> CInt
mode2Int AbsoluteSeek = (0)
{-# LINE 313 "libraries/unix/System/Posix/IO/Common.hsc" #-}
mode2Int RelativeSeek = (1)
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mode2Int SeekFromEnd  = (2)
{-# LINE 315 "libraries/unix/System/Posix/IO/Common.hsc" #-}

-- | May throw an exception if this is an invalid descriptor.
fdSeek :: Fd -> SeekMode -> FileOffset -> IO FileOffset
fdSeek (Fd fd) mode off =
  throwErrnoIfMinus1 "fdSeek" (Base.c_lseek fd off (mode2Int mode))

-- -----------------------------------------------------------------------------
-- Locking

data LockRequest = ReadLock
                 | WriteLock
                 | Unlock

type FileLock = (LockRequest, SeekMode, FileOffset, FileOffset)

-- | May throw an exception if this is an invalid descriptor.
getLock :: Fd -> FileLock -> IO (Maybe (ProcessID, FileLock))
getLock (Fd fd) lock =
  allocaLock lock $ \p_flock -> do
    throwErrnoIfMinus1_ "getLock" (Base.c_fcntl_lock fd (5) p_flock)
{-# LINE 335 "libraries/unix/System/Posix/IO/Common.hsc" #-}
    result <- bytes2ProcessIDAndLock p_flock
    return (maybeResult result)
  where
    maybeResult (_, (Unlock, _, _, _)) = Nothing
    maybeResult x = Just x

allocaLock :: FileLock -> (Ptr Base.CFLock -> IO a) -> IO a
allocaLock (lockreq, mode, start, len) io =
  allocaBytes (32) $ \p -> do
{-# LINE 344 "libraries/unix/System/Posix/IO/Common.hsc" #-}
    ((\hsc_ptr -> pokeByteOff hsc_ptr 0))   p (lockReq2Int lockreq :: CShort)
{-# LINE 345 "libraries/unix/System/Posix/IO/Common.hsc" #-}
    ((\hsc_ptr -> pokeByteOff hsc_ptr 2)) p (fromIntegral (mode2Int mode) :: CShort)
{-# LINE 346 "libraries/unix/System/Posix/IO/Common.hsc" #-}
    ((\hsc_ptr -> pokeByteOff hsc_ptr 8))  p start
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    ((\hsc_ptr -> pokeByteOff hsc_ptr 16))    p len
{-# LINE 348 "libraries/unix/System/Posix/IO/Common.hsc" #-}
    io p

lockReq2Int :: LockRequest -> CShort
lockReq2Int ReadLock  = (0)
{-# LINE 352 "libraries/unix/System/Posix/IO/Common.hsc" #-}
lockReq2Int WriteLock = (1)
{-# LINE 353 "libraries/unix/System/Posix/IO/Common.hsc" #-}
lockReq2Int Unlock    = (2)
{-# LINE 354 "libraries/unix/System/Posix/IO/Common.hsc" #-}

bytes2ProcessIDAndLock :: Ptr Base.CFLock -> IO (ProcessID, FileLock)
bytes2ProcessIDAndLock p = do
  req   <- ((\hsc_ptr -> peekByteOff hsc_ptr 0))   p
{-# LINE 358 "libraries/unix/System/Posix/IO/Common.hsc" #-}
  mode  <- ((\hsc_ptr -> peekByteOff hsc_ptr 2)) p
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  start <- ((\hsc_ptr -> peekByteOff hsc_ptr 8))  p
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  len   <- ((\hsc_ptr -> peekByteOff hsc_ptr 16))    p
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  pid   <- ((\hsc_ptr -> peekByteOff hsc_ptr 24))    p
{-# LINE 362 "libraries/unix/System/Posix/IO/Common.hsc" #-}
  return (pid, (int2req req, int2mode mode, start, len))
 where
  int2req :: CShort -> LockRequest
  int2req (0) = ReadLock
{-# LINE 366 "libraries/unix/System/Posix/IO/Common.hsc" #-}
  int2req (1) = WriteLock
{-# LINE 367 "libraries/unix/System/Posix/IO/Common.hsc" #-}
  int2req (2) = Unlock
{-# LINE 368 "libraries/unix/System/Posix/IO/Common.hsc" #-}
  int2req _ = error $ "int2req: bad argument"

  int2mode :: CShort -> SeekMode
  int2mode (0) = AbsoluteSeek
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  int2mode (1) = RelativeSeek
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  int2mode (2) = SeekFromEnd
{-# LINE 374 "libraries/unix/System/Posix/IO/Common.hsc" #-}
  int2mode _ = error $ "int2mode: bad argument"

-- | May throw an exception if this is an invalid descriptor.
setLock :: Fd -> FileLock -> IO ()
setLock (Fd fd) lock = do
  allocaLock lock $ \p_flock ->
    throwErrnoIfMinus1_ "setLock" (Base.c_fcntl_lock fd (6) p_flock)
{-# LINE 381 "libraries/unix/System/Posix/IO/Common.hsc" #-}

-- | May throw an exception if this is an invalid descriptor.
waitToSetLock :: Fd -> FileLock -> IO ()
waitToSetLock (Fd fd) lock = do
  allocaLock lock $ \p_flock ->
    throwErrnoIfMinus1_ "waitToSetLock"
        (Base.c_fcntl_lock fd (7) p_flock)
{-# LINE 388 "libraries/unix/System/Posix/IO/Common.hsc" #-}

-- -----------------------------------------------------------------------------
-- fd{Read,Write}

-- | Read data from an 'Fd' and convert it to a 'String' using the locale encoding.
-- Throws an exception if this is an invalid descriptor, or EOF has been
-- reached.
fdRead :: Fd
       -> ByteCount -- ^How many bytes to read
       -> IO (String, ByteCount) -- ^The bytes read, how many bytes were read.
fdRead _fd 0 = return ("", 0)
fdRead fd nbytes = do
    allocaBytes (fromIntegral nbytes) $ \ buf -> do
    rc <- fdReadBuf fd buf nbytes
    case rc of
      0 -> ioError (ioeSetErrorString (mkIOError EOF "fdRead" Nothing Nothing) "EOF")
      n -> do
       s <- peekCStringLen (castPtr buf, fromIntegral n)
       return (s, n)

-- | Read data from an 'Fd' into memory.  This is exactly equivalent
-- to the POSIX @read@ function.
fdReadBuf :: Fd
          -> Ptr Word8 -- ^ Memory in which to put the data
          -> ByteCount -- ^ Maximum number of bytes to read
          -> IO ByteCount -- ^ Number of bytes read (zero for EOF)
fdReadBuf _fd _buf 0 = return 0
fdReadBuf fd buf nbytes =
  fmap fromIntegral $
    throwErrnoIfMinus1Retry "fdReadBuf" $
      c_safe_read (fromIntegral fd) (castPtr buf) nbytes

foreign import ccall safe "read"
   c_safe_read :: CInt -> Ptr CChar -> CSize -> IO CSsize

-- | Write a 'String' to an 'Fd' using the locale encoding.
fdWrite :: Fd -> String -> IO ByteCount
fdWrite fd str =
  withCStringLen str $ \ (buf,len) ->
    fdWriteBuf fd (castPtr buf) (fromIntegral len)

-- | Write data from memory to an 'Fd'.  This is exactly equivalent
-- to the POSIX @write@ function.
fdWriteBuf :: Fd
           -> Ptr Word8    -- ^ Memory containing the data to write
           -> ByteCount    -- ^ Maximum number of bytes to write
           -> IO ByteCount -- ^ Number of bytes written
fdWriteBuf fd buf len =
  fmap fromIntegral $
    throwErrnoIfMinus1Retry "fdWriteBuf" $
      c_safe_write (fromIntegral fd) (castPtr buf) len

foreign import ccall safe "write"
   c_safe_write :: CInt -> Ptr CChar -> CSize -> IO CSsize