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 func sendFile(fd *netFD, r io.Reader) (written int64, err error, handled bool) {
  22         var n int64 = 0 // by default, copy until EOF.
  23
  24         lr, ok := r.(*io.LimitedReader)
  25         if ok {
  26                 n, r = lr.N, lr.R
  27                 if n <= 0 {
  28                         return 0, nil, true
  29                 }
  30         }
  31
  32         f, ok := r.(*os.File)
  33         if !ok {
  34                 return 0, nil, false
  35         }
  36
  37         written, err = poll.SendFile(&fd.pfd, syscall.Handle(f.Fd()), n)
  38         if err != nil {
  39                 err = wrapSyscallError("transmitfile", err)
  40         }
  41
  42         // If any byte was copied, regardless of any error
  43         // encountered mid-way, handled must be set to true.
  44         handled = written > 0
  45
  46         return
  47 }