libgo/go/net/sendfile_solaris.go

   1 // Copyright 2015 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         // Solaris uses 0 as the "until EOF" value. If you pass in more bytes than the
  22         // file contains, it will loop back to the beginning ad nauseam until it's sent
  23         // exactly the number of bytes told to. As such, we need to know exactly how many
  24         // bytes to send.
  25         var remain int64 = 0
  26
  27         lr, ok := r.(*io.LimitedReader)
  28         if ok {
  29                 remain, r = lr.N, lr.R
  30                 if remain <= 0 {
  31                         return 0, nil, true
  32                 }
  33         }
  34         f, ok := r.(*os.File)
  35         if !ok {
  36                 return 0, nil, false
  37         }
  38
  39         if remain == 0 {
  40                 fi, err := f.Stat()
  41                 if err != nil {
  42                         return 0, err, false
  43                 }
  44
  45                 remain = fi.Size()
  46         }
  47
  48         // The other quirk with Solaris's sendfile implementation is that it doesn't
  49         // use the current position of the file -- if you pass it offset 0, it starts
  50         // from offset 0. There's no way to tell it "start from current position", so
  51         // we have to manage that explicitly.
  52         pos, err := f.Seek(0, io.SeekCurrent)
  53         if err != nil {
  54                 return 0, err, false
  55         }
  56
  57         written, err = poll.SendFile(&c.pfd, int(f.Fd()), pos, remain)
  58
  59         if lr != nil {
  60                 lr.N = remain - written
  61         }
  62         return written, wrapSyscallError("sendfile", err), written > 0
  63 }