(* Copyright (C) 2017 Matthew Fluet.
 * Copyright (C) 1999-2008 Henry Cejtin, Matthew Fluet, Suresh
 *    Jagannathan, and Stephen Weeks.
 * Copyright (C) 1997-2000 NEC Research Institute.
 *
 * MLton is released under a BSD-style license.
 * See the file MLton-LICENSE for details.
 *)

structure PosixIO: POSIX_IO =
struct

structure Prim = PrimitiveFFI.Posix.IO
open Prim
structure FileDesc = PrePosix.FileDesc
structure PId = PrePosix.PId

structure Error = PosixError
structure SysCall = Error.SysCall
structure FS = PosixFileSys

type file_desc = FileDesc.t
type pid = PId.t

local
   val a: C_Fd.t array = Array.array (2, C_Fd.fromInt 0)
   val get = fn i => FileDesc.fromRep (Array.sub (a, i))
in
   fun pipe () =
      SysCall.syscall
      (fn () =>
       (Prim.pipe a,
        fn _ => {infd = get 0,
                 outfd = get 1}))
end

fun dup fd =
   (FileDesc.fromRep o SysCall.simpleResult)
   (fn () => Prim.dup (FileDesc.toRep fd))

fun dup2 {new, old} =
   SysCall.simple
   (fn () => Prim.dup2 (FileDesc.toRep old, FileDesc.toRep new))

fun close fd =
   SysCall.simpleRestart
   (fn () => Prim.close (FileDesc.toRep fd))

structure FD =
   struct
      structure Flags = BitFlags(structure S = C_Int)
      open FD Flags
      val cloexec = CLOEXEC
   end

structure O = PosixFileSys.O

datatype open_mode = datatype PosixFileSys.open_mode

fun dupfd {base, old} =
   (FileDesc.fromRep o SysCall.simpleResultRestart)
   (fn () => Prim.fcntl3 (FileDesc.toRep old, F_DUPFD, FileDesc.toRep base))

fun getfd fd =
   SysCall.simpleResultRestart 
   (fn () => Prim.fcntl2 (FileDesc.toRep fd, F_GETFD))

fun setfd (fd, flags): unit =
   SysCall.simpleRestart
   (fn () => Prim.fcntl3 (FileDesc.toRep fd, F_SETFD, flags))

fun getfl fd : O.flags * open_mode =
   let 
      val n = SysCall.simpleResultRestart
              (fn () => Prim.fcntl2 (FileDesc.toRep fd, F_GETFL))
      val flags = C_Int.andb (n, C_Int.notb O_ACCMODE)
      val mode = C_Int.andb (n, O_ACCMODE)
   in (flags, PosixFileSys.flagsToOpenMode mode)
   end

fun setfl (fd, flags: O.flags): unit  =
   SysCall.simpleRestart
   (fn () => Prim.fcntl3 (FileDesc.toRep fd, F_SETFL, flags))

datatype whence = SEEK_SET | SEEK_CUR | SEEK_END

val whenceToInt =
   fn SEEK_SET => Prim.SEEK_SET
    | SEEK_CUR => Prim.SEEK_CUR
    | SEEK_END => Prim.SEEK_END

fun lseek (fd, n: Position.int, w: whence): Position.int =
   SysCall.simpleResult'
   ({errVal = C_Off.fromInt ~1}, fn () =>
    Prim.lseek (FileDesc.toRep fd, n, whenceToInt w))

fun fsync fd : unit =
   SysCall.simple
   (fn () => Prim.fsync (FileDesc.toRep fd))

val whenceToInt =
   fn SEEK_SET => Prim.FLock.SEEK_SET
    | SEEK_CUR => Prim.FLock.SEEK_CUR
    | SEEK_END => Prim.FLock.SEEK_END

fun intToWhence n =
   if n = Prim.FLock.SEEK_SET
      then SEEK_SET
   else if n = Prim.FLock.SEEK_CUR
      then SEEK_CUR
   else if n = Prim.FLock.SEEK_END
      then SEEK_END
   else raise Fail "Posix.IO.intToWhence"

datatype lock_type = F_RDLCK | F_WRLCK | F_UNLCK

val lockTypeToInt =
   fn F_RDLCK => Prim.FLock.F_RDLCK
    | F_WRLCK => Prim.FLock.F_WRLCK
    | F_UNLCK => Prim.FLock.F_UNLCK

fun intToLockType n =
   if n = Prim.FLock.F_RDLCK
      then F_RDLCK
   else if n = Prim.FLock.F_WRLCK
      then F_WRLCK
   else if n = Prim.FLock.F_UNLCK
      then F_UNLCK
   else raise Fail "Posix.IO.intToLockType"

structure FLock =
   struct
      open FLock

      type flock = {ltype: lock_type,
                    whence: whence,
                    start: Position.int,
                    len: Position.int,
                    pid: pid option}

      fun flock l = l
      val ltype: flock -> lock_type = #ltype
      val whence: flock -> whence = #whence
      val start: flock -> Position.int = #start
      val len: flock -> Position.int = #len
      val pid: flock -> pid option = #pid
   end

local
   structure P = Prim.FLock
   fun make
      (cmd, usepid)
      (fd, {ltype, whence, start, len, ...}: FLock.flock)
      : FLock.flock  =
      SysCall.syscallRestart
      (fn () =>
       ((P.setType (lockTypeToInt ltype)
         ; P.setWhence (whenceToInt whence)
         ; P.setStart start
         ; P.setLen len
         ; P.fcntl (FileDesc.toRep fd, cmd)), fn _ =>
        {ltype = intToLockType (P.getType ()),
         whence = intToWhence (P.getWhence ()),
         start = P.getStart (),
         len = P.getLen (),
         pid = if usepid then SOME (PId.fromRep (P.getPId ()))
               else NONE}))
in
   val getlk = make (FLock.F_GETLK, true)
   val setlk = make (FLock.F_SETLK, false)
   val setlkw = make (FLock.F_SETLKW, false)
end

(* Adapted from SML/NJ sources. *)
(* posix-bin-prim-io.sml
 *
 * COPYRIGHT (c) 1995 AT&T Bell Laboratories.
 *
 * This implements the UNIX version of the OS specific binary primitive
 * IO structure.  The Text IO version is implemented by a trivial translation
 * of these operations (see posix-text-prim-io.sml).
 *
 *)
local
   val pos0 = Position.fromInt 0
   fun isReg fd = FS.ST.isReg(FS.fstat fd)
   fun posFns (closed, fd) = 
      if (isReg fd)
         then let
                 val pos = ref pos0
                 fun getPos () = !pos
                 fun setPos p = (if !closed 
                                    then raise IO.ClosedStream 
                                 else ();
                                    pos := lseek(fd,p,SEEK_SET))
                 fun endPos () = (if !closed 
                                     then raise IO.ClosedStream 
                                  else ();
                                     FS.ST.size(FS.fstat fd))
                 fun verifyPos () = let
                                       val curPos = lseek(fd, pos0, SEEK_CUR)
                                    in
                                       pos := curPos; curPos
                                    end
                 val _ = verifyPos ()
              in
                 {pos = pos,
                  getPos = SOME getPos,
                  setPos = SOME setPos,
                  endPos = SOME endPos,
                  verifyPos = SOME verifyPos}
              end
      else {pos = ref pos0,
            getPos = NONE, 
            setPos = NONE, 
            endPos = NONE, 
            verifyPos = NONE}

   fun make {RD, WR, fromVector, readArr, setMode, toArraySlice, toVectorSlice,
             vectorLength, writeArr, writeVec} =
      let
         val primReadArr = fn (fd, buf, i, sz) =>
            readArr (FileDesc.toRep fd, buf, C_Int.fromInt i, C_Size.fromInt sz)
         val primWriteArr = fn (fd, buf, i, sz) =>
            writeArr (FileDesc.toRep fd, buf, C_Int.fromInt i, C_Size.fromInt sz)
         val primWriteVec = fn (fd, buf, i, sz) =>
            writeVec (FileDesc.toRep fd, buf, C_Int.fromInt i, C_Size.fromInt sz)
         val setMode =
            fn fd =>
            if let
                  open Primitive.MLton.Platform.OS
               in
                  case host of
                     MinGW => true
                   | _ => false
               end
               then setMode (FileDesc.toRep fd)
            else ()
         fun readArr (fd, sl): int =
            let
               val (buf, i, sz) = ArraySlice.base (toArraySlice sl)
               val bytesRead =
                  SysCall.simpleResultRestart'
                  ({errVal = C_SSize.castFromFixedInt ~1}, fn () => 
                   primReadArr (fd, buf, i, sz))
               val bytesRead = C_SSize.toInt bytesRead
            in
               bytesRead
            end
         fun readVec (fd, n) =
            let
               val buf = Array.alloc n
               val bytesRead = 
                  SysCall.simpleResultRestart'
                  ({errVal = C_SSize.castFromFixedInt ~1}, fn () => 
                   primReadArr (fd, buf, 0, n))
               val bytesRead = C_SSize.toInt bytesRead
            in 
               fromVector
               (if n = bytesRead
                   then Vector.unsafeFromArray buf
                   else ArraySlice.vector (ArraySlice.slice (buf, 0, SOME bytesRead)))
            end
         fun writeArr (fd, sl): int =
            let
               val (buf, i, sz) = ArraySlice.base (toArraySlice sl)
               val bytesWrote =
                  SysCall.simpleResultRestart'
                  ({errVal = C_SSize.castFromFixedInt ~1}, fn () => 
                   primWriteArr (fd, buf, i, sz))
               val bytesWrote = C_SSize.toInt bytesWrote
            in
               bytesWrote
            end
         fun writeVec (fd, sl): int =
            let
               val (buf, i, sz) = VectorSlice.base (toVectorSlice sl)
               val bytesWrote =
                  SysCall.simpleResultRestart'
                  ({errVal = C_SSize.castFromFixedInt ~1}, fn () => 
                   primWriteVec (fd, buf, i, sz))
               val bytesWrote = C_SSize.toInt bytesWrote
            in
               bytesWrote
            end
         fun mkReader {fd, name, initBlkMode} =
            let
               val closed = ref false
               val {pos, getPos, setPos, endPos, verifyPos} =
                  posFns (closed, fd)
               val blocking = ref initBlkMode
               fun blockingOn () = 
                  (setfl(fd, O.flags[]); blocking := true)
               fun blockingOff () = 
                  (setfl(fd, O.nonblock); blocking := false)
               fun ensureOpen () = 
                  if !closed then raise IO.ClosedStream else ()
               fun incPos k = pos := Position.+ (!pos, Position.fromInt k)
               val readVec = fn n => 
                  let val v = readVec (fd, n)
                  in incPos (vectorLength v); v
                  end
               val readArr = fn x => 
                  let val k = readArr (fd, x)
                  in incPos k; k
                  end
               fun blockWrap f x =
                  (ensureOpen ();
                   if !blocking then () else blockingOn ();
                   f x)
               fun noBlockWrap f x =
                  (ensureOpen ();
                   if !blocking then blockingOff () else ();
                   (SOME (f x)
                    handle (e as PosixError.SysErr (_, cause)) =>
                       if cause = SOME PosixError.again then NONE else raise e))
               val close = 
                  fn () => if !closed then () else (closed := true; close fd)
               val avail = 
                  if isReg fd
                     then fn () => if !closed 
                                      then SOME 0
                                   else SOME (Position.toInt
                                              (Position.-
                                               (FS.ST.size (FS.fstat fd),
                                                !pos)))
                  else fn () => if !closed then SOME 0 else NONE
               val () = setMode fd
            in
               RD {avail = avail,
                   block = NONE,
                   canInput = NONE,
                   chunkSize = Int32.toInt Primitive.Controls.bufSize,
                   close = close,
                   endPos = endPos,
                   getPos = getPos,
                   ioDesc = SOME (FS.fdToIOD fd),
                   name = name,
                   readArr = SOME (blockWrap readArr),
                   readArrNB = SOME (noBlockWrap readArr),
                   readVec = SOME (blockWrap readVec),
                   readVecNB = SOME (noBlockWrap readVec),
                   setPos = setPos,
                   verifyPos = verifyPos}
            end
         fun mkWriter {fd, name, initBlkMode, appendMode, chunkSize} =
            let
               val closed = ref false
               val {pos, getPos, setPos, endPos, verifyPos} =
                  posFns (closed, fd)
               fun incPos k = (pos := Position.+ (!pos, Position.fromInt k); k)
               val blocking = ref initBlkMode
               val appendFlgs = O.flags(if appendMode then [O.append] else [])
               fun updateStatus () = 
                  let
                     val flgs = if !blocking
                                   then appendFlgs
                                else O.flags [O.nonblock, appendFlgs]
                  in
                     setfl(fd, flgs)
                  end
               fun ensureOpen () = 
                  if !closed then raise IO.ClosedStream else ()
               fun ensureBlock x = 
                  if !blocking then () else (blocking := x; updateStatus ())
               fun putV x = incPos (writeVec x)
               fun putA x = incPos (writeArr x)
               fun write (put, block) arg = 
                  (ensureOpen (); ensureBlock block; put (fd, arg))
               fun handleBlock writer arg = 
                  SOME(writer arg)
                  handle (e as PosixError.SysErr (_, cause)) =>
                     if cause = SOME PosixError.again then NONE else raise e
               val close = 
                  fn () => if !closed then () else (closed := true; close fd)
               val () = setMode fd
            in
               WR {block = NONE,
                   canOutput = NONE,
                   chunkSize = chunkSize,
                   close = close,
                   endPos = endPos,
                   getPos = getPos,
                   ioDesc = SOME (FS.fdToIOD fd),
                   name = name,
                   setPos = setPos,
                   verifyPos = verifyPos,
                   writeArr = SOME (write (putA, true)),
                   writeArrNB = SOME (handleBlock (write (putA, false))),
                   writeVec = SOME (write (putV, true)),
                   writeVecNB = SOME (handleBlock (write (putV, false)))}
            end
      in
         {mkReader = mkReader,
          mkWriter = mkWriter,
          readArr = readArr,
          readVec = readVec,
          writeArr = writeArr,
          writeVec = writeVec}
      end
in
   val {mkReader = mkBinReader, mkWriter = mkBinWriter,
        readArr, readVec, writeArr, writeVec} =
      make {RD = BinPrimIO.RD,
            WR = BinPrimIO.WR,
            fromVector = Word8Vector.fromPoly,
            readArr = readWord8,
            setMode = Prim.setbin,
            toArraySlice = Word8ArraySlice.toPoly,
            toVectorSlice = Word8VectorSlice.toPoly,
            vectorLength = Word8Vector.length,
            writeArr = writeWord8Arr,
            writeVec = writeWord8Vec}
   val {mkReader = mkTextReader, mkWriter = mkTextWriter, ...} =
      make {RD = TextPrimIO.RD,
            WR = TextPrimIO.WR,
            fromVector = fn v => v,
            readArr = readChar8,
            setMode = Prim.settext,
            toArraySlice = CharArraySlice.toPoly,
            toVectorSlice = CharVectorSlice.toPoly,
            vectorLength = CharVector.length,
            writeArr = writeChar8Arr,
            writeVec = writeChar8Vec}
end

end