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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.
//go:build (darwin && !ios) || dragonfly || freebsd || solaris
package net
import (
"internal/poll"
"io"
"syscall"
)
const supportsSendfile = true
// sendFile copies the contents of r to c using the sendfile
// system call to minimize copies.
//
// if handled == true, sendFile returns the number (potentially zero) 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 = 0 // 0 writes the entire file
lr, ok := r.(*io.LimitedReader)
if ok {
remain, r = lr.N, lr.R
if remain <= 0 {
return 0, nil, true
}
}
// r might be an *os.File or an os.fileWithoutWriteTo.
// Type assert to an interface rather than *os.File directly to handle the latter case.
f, ok := r.(syscall.Conn)
if !ok {
return 0, nil, false
}
sc, err := f.SyscallConn()
if err != nil {
return 0, nil, false
}
var werr error
err = sc.Read(func(fd uintptr) bool {
written, werr, handled = poll.SendFile(&c.pfd, int(fd), remain)
return true
})
if err == nil {
err = werr
}
if lr != nil {
lr.N = remain - written
}
return written, wrapSyscallError("sendfile", err), handled
}
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