blob: 63ca9d47b8ae288219b34aaa8e844049e74c037e [file] [log] [blame]
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package net
import (
"internal/poll"
"io"
"os"
)
// sendFile copies the contents of r to c using the sendfile
// system call to minimize copies.
//
// if handled == true, sendFile returns the number of bytes copied and any
// non-EOF error.
//
// if handled == false, sendFile performed no work.
func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
// Solaris uses 0 as the "until EOF" value. If you pass in more bytes than the
// file contains, it will loop back to the beginning ad nauseam until it's sent
// exactly the number of bytes told to. As such, we need to know exactly how many
// bytes to send.
var remain int64 = 0
lr, ok := r.(*io.LimitedReader)
if ok {
remain, r = lr.N, lr.R
if remain <= 0 {
return 0, nil, true
}
}
f, ok := r.(*os.File)
if !ok {
return 0, nil, false
}
if remain == 0 {
fi, err := f.Stat()
if err != nil {
return 0, err, false
}
remain = fi.Size()
}
// The other quirk with Solaris's sendfile implementation is that it doesn't
// use the current position of the file -- if you pass it offset 0, it starts
// from offset 0. There's no way to tell it "start from current position", so
// we have to manage that explicitly.
pos, err := f.Seek(0, io.SeekCurrent)
if err != nil {
return 0, err, false
}
written, err = poll.SendFile(&c.pfd, int(f.Fd()), pos, remain)
if lr != nil {
lr.N = remain - written
}
return written, wrapSyscallError("sendfile", err), written > 0
}