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// 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 (
"internal/poll"
"io"
"os"
"syscall"
)
const supportsSendfile = true
// sendFile copies the contents of r to c using the TransmitFile
// 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(fd *netFD, r io.Reader) (written int64, err error, handled bool) {
var n int64 = 0 // by default, copy until EOF.
lr, ok := r.(*io.LimitedReader)
if ok {
n, r = lr.N, lr.R
if n <= 0 {
return 0, nil, true
}
}
f, ok := r.(*os.File)
if !ok {
return 0, nil, false
}
written, err = poll.SendFile(&fd.pfd, syscall.Handle(f.Fd()), n)
if err != nil {
err = wrapSyscallError("transmitfile", err)
}
// If any byte was copied, regardless of any error
// encountered mid-way, handled must be set to true.
handled = written > 0
return
}
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