blob: 350abe451f37854b1d26889ca5a243010e51f251 [file] [log] [blame]
// Copyright 2011 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 (
"io"
"os"
"syscall"
)
// maxSendfileSize is the largest chunk size we ask the kernel to copy
// at a time.
const maxSendfileSize int = 4 << 20
// 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) {
var remain int64 = 1 << 62 // by default, copy until EOF
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
}
c.wio.Lock()
defer c.wio.Unlock()
c.incref()
defer c.decref()
if c.wdeadline_delta > 0 {
// This is a little odd that we're setting the timeout
// for the entire file but Write has the same issue
// (if one slurps the whole file into memory and
// do one large Write). At least they're consistent.
c.wdeadline = pollserver.Now() + c.wdeadline_delta
} else {
c.wdeadline = 0
}
dst := c.sysfd
src := f.Fd()
for remain > 0 {
n := maxSendfileSize
if int64(n) > remain {
n = int(remain)
}
n, errno := syscall.Sendfile(dst, src, nil, n)
if n > 0 {
written += int64(n)
remain -= int64(n)
}
if n == 0 && errno == nil {
break
}
if errno == syscall.EAGAIN && c.wdeadline >= 0 {
pollserver.WaitWrite(c)
continue
}
if errno != nil {
// This includes syscall.ENOSYS (no kernel
// support) and syscall.EINVAL (fd types which
// don't implement sendfile together)
err = &OpError{"sendfile", c.net, c.raddr, errno}
break
}
}
if lr != nil {
lr.N = remain
}
return written, err, written > 0
}