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.
13 // maxSendfileSize is the largest chunk size we ask the kernel to copy
15 const maxSendfileSize int = 4 << 20
17 // sendFile copies the contents of r to c using the sendfile
18 // system call to minimize copies.
20 // if handled == true, sendFile returns the number of bytes copied and any
23 // if handled == false, sendFile performed no work.
24 func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
25 // FreeBSD uses 0 as the "until EOF" value. If you pass in more bytes than the
26 // file contains, it will loop back to the beginning ad nauseum until it's sent
27 // exactly the number of bytes told to. As such, we need to know exactly how many
31 lr, ok := r.(*io.LimitedReader)
33 remain, r = lr.N, lr.R
52 // The other quirk with FreeBSD's sendfile implementation is that it doesn't
53 // use the current position of the file -- if you pass it offset 0, it starts
54 // from offset 0. There's no way to tell it "start from current position", so
55 // we have to manage that explicitly.
56 pos, err := f.Seek(0, os.SEEK_CUR)
63 if err := c.incref(false); err != nil {
72 if int64(n) > remain {
76 n, err1 := syscall.Sendfile(dst, src, &pos1, n)
82 if n == 0 && err1 == nil {
85 if err1 == syscall.EAGAIN {
86 if err1 = c.pollServer.WaitWrite(c); err1 == nil {
90 if err1 == syscall.EINTR {
94 // This includes syscall.ENOSYS (no kernel
95 // support) and syscall.EINVAL (fd types which
96 // don't implement sendfile together)
97 err = &OpError{"sendfile", c.net, c.raddr, err1}
104 return written, err, written > 0