libgo/go/net/sendfile_linux.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 )
  12
  13 // sendFile copies the contents of r to c using the sendfile
  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 func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
  21         var remain int64 = 1 << 62 // by default, copy until EOF
  22
  23         lr, ok := r.(*io.LimitedReader)
  24         if ok {
  25                 remain, r = lr.N, lr.R
  26                 if remain <= 0 {
  27                         return 0, nil, true
  28                 }
  29         }
  30         f, ok := r.(*os.File)
  31         if !ok {
  32                 return 0, nil, false
  33         }
  34
  35         written, err = poll.SendFile(&c.pfd, int(f.Fd()), remain)
  36
  37         if lr != nil {
  38                 lr.N = remain - written
  39         }
  40         return written, wrapSyscallError("sendfile", err), written > 0
  41 }