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         "io"
   9         "os"
  10         "syscall"
  11 )
  12
  13 // sendFile copies the contents of r to c using the TransmitFile
  14 // system call to minimize copies.
  15 //
  16 // if handled == true, sendFile returns the number of bytes copied and any
  17 // non-EOF error.
  18 //
  19 // if handled == false, sendFile performed no work.
  20 //
  21 // Note that sendfile for windows does not suppport >2GB file.
  22 func sendFile(fd *netFD, r io.Reader) (written int64, err error, handled bool) {
  23         var n int64 = 0 // by default, copy until EOF
  24
  25         lr, ok := r.(*io.LimitedReader)
  26         if ok {
  27                 n, r = lr.N, lr.R
  28                 if n <= 0 {
  29                         return 0, nil, true
  30                 }
  31         }
  32         f, ok := r.(*os.File)
  33         if !ok {
  34                 return 0, nil, false
  35         }
  36
  37         if err := fd.writeLock(); err != nil {
  38                 return 0, err, true
  39         }
  40         defer fd.writeUnlock()
  41
  42         o := &fd.wop
  43         o.qty = uint32(n)
  44         o.handle = syscall.Handle(f.Fd())
  45         done, err := wsrv.ExecIO(o, "TransmitFile", func(o *operation) error {
  46                 return syscall.TransmitFile(o.fd.sysfd, o.handle, o.qty, 0, &o.o, nil, syscall.TF_WRITE_BEHIND)
  47         })
  48         if err != nil {
  49                 return 0, err, false
  50         }
  51         if lr != nil {
  52                 lr.N -= int64(done)
  53         }
  54         return int64(done), nil, true
  55 }