libgo/go/net/sendfile_glibc.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 // +build hurd linux
   6
   7 package net
   8
   9 import (
  10         "internal/poll"
  11         "io"
  12         "os"
  13 )
  14
  15 // sendFile copies the contents of r to c using the sendfile
  16 // system call to minimize copies.
  17 //
  18 // if handled == true, sendFile returns the number of bytes copied and any
  19 // non-EOF error.
  20 //
  21 // if handled == false, sendFile performed no work.
  22 func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
  23         var remain int64 = 1 << 62 // by default, copy until EOF
  24
  25         lr, ok := r.(*io.LimitedReader)
  26         if ok {
  27                 remain, r = lr.N, lr.R
  28                 if remain <= 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         sc, err := f.SyscallConn()
  38         if err != nil {
  39                 return 0, nil, false
  40         }
  41
  42         var werr error
  43         err = sc.Read(func(fd uintptr) bool {
  44                 written, werr = poll.SendFile(&c.pfd, int(fd), remain)
  45                 return true
  46         })
  47         if werr == nil {
  48                 werr = err
  49         }
  50
  51         if lr != nil {
  52                 lr.N = remain - written
  53         }
  54         return written, wrapSyscallError("sendfile", err), written > 0
  55 }