libgo/go/net/sendfile_windows.go

   1 // Copyright 2011 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package net
   6
   7 import (
   8         "internal/poll"
   9         "io"
  10         "os"
  11         "syscall"
  12 )
  13
  14 // sendFile copies the contents of r to c using the TransmitFile
  15 // system call to minimize copies.
  16 //
  17 // if handled == true, sendFile returns the number of bytes copied and any
  18 // non-EOF error.
  19 //
  20 // if handled == false, sendFile performed no work.
  21 //
  22 // Note that sendfile for windows does not support >2GB file.
  23 func sendFile(fd *netFD, r io.Reader) (written int64, err error, handled bool) {
  24         var n int64 = 0 // by default, copy until EOF
  25
  26         lr, ok := r.(*io.LimitedReader)
  27         if ok {
  28                 n, r = lr.N, lr.R
  29                 if n <= 0 {
  30                         return 0, nil, true
  31                 }
  32         }
  33         f, ok := r.(*os.File)
  34         if !ok {
  35                 return 0, nil, false
  36         }
  37
  38         done, err := poll.SendFile(&fd.pfd, syscall.Handle(f.Fd()), n)
  39
  40         if err != nil {
  41                 return 0, wrapSyscallError("transmitfile", err), false
  42         }
  43         if lr != nil {
  44                 lr.N -= int64(done)
  45         }
  46         return int64(done), nil, true
  47 }