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
5package net
6
7import (
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.
20func 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}
42