res.Body.Close()

	// Force child to exit cleanly.
	Post(fmt.Sprintf("http://%s/quit", ln.Addr()), "", nil)
	child.Wait()

	rx := regexp.MustCompile(`\b(n64:)?sendfile(64)?\(`)
	out := buf.String()
	if !rx.MatchString(out) {
		t.Errorf("no sendfile system call found in:\n%s", out)
	}
}

func getBody(t *testing.T, testName string, req Request, client *Client) (*Response, []byte) {
	r, err := client.Do(&req)

//go:cgo_import_dynamic libc___xnet_connect __xnet_connect "libsocket.so"
//go:cgo_import_dynamic libc_mmap mmap "libc.so"
//go:cgo_import_dynamic libc_munmap munmap "libc.so"
//go:cgo_import_dynamic libc_sendfile sendfile "libsendfile.so"
//go:cgo_import_dynamic libc___xnet_sendto __xnet_sendto "libsocket.so"
//go:cgo_import_dynamic libc___xnet_socket __xnet_socket "libsocket.so"

	return
}

var libc_sysctl_trampoline_addr uintptr

//go:cgo_import_dynamic libc_sysctl sysctl "/usr/lib/libSystem.B.dylib"

// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT

func sendfile(infd int, outfd int, offset int64, len *int64, hdtr unsafe.Pointer, flags int) (err error) {

	return
}

var libc_sysctl_trampoline_addr uintptr

//go:cgo_import_dynamic libc_sysctl sysctl "/usr/lib/libSystem.B.dylib"

// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT

func sendfile(infd int, outfd int, offset int64, len *int64, hdtr unsafe.Pointer, flags int) (err error) {

	return mountSetattr(dirfd, pathname, flags, attr, unsafe.Sizeof(*attr))
}

func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
	if raceenabled {
		raceReleaseMerge(unsafe.Pointer(&ioSync))
	}
	return sendfile(outfd, infd, offset, count)
}

// Sendto
// Recvfrom
// Socketpair

/*
 * Direct access
 */

	w.pc.nwrite += int64(n)
	return
}

// ReadFrom exposes persistConnWriter's underlying Conn to io.Copy and if
// the Conn implements io.ReaderFrom, it can take advantage of optimizations
// such as sendfile.
func (w persistConnWriter) ReadFrom(r io.Reader) (n int64, err error) {
	n, err = io.Copy(w.pc.conn, r)
	w.pc.nwrite += n
	return
}

var _ io.ReaderFrom = (*persistConnWriter)(nil)