forked from brutella/can
/
readwritecloser.go
104 lines (81 loc) · 2.2 KB
/
readwritecloser.go
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package can
import (
"errors"
"io"
"golang.org/x/sys/unix"
)
// The Reader interface extends the `io.Reader` interface by method
// to read a frame.
type Reader interface {
io.Reader
ReadFrame(*Frame) error
}
// The Writer interface extends the `io.Writer` interface by method
// to write a frame.
type Writer interface {
io.Writer
WriteFrame(Frame) error
}
// The ReadWriteCloser interface combines the Reader and Writer and
// `io.Closer` interface.
type ReadWriteCloser interface {
Reader
Writer
io.Closer
setFilter(filter []unix.CanFilter) error
deleteFilter() error
}
type readWriteCloser struct {
rwc io.ReadWriteCloser
socket int
}
// NewReadWriteCloser returns a ReadWriteCloser for an `io.ReadWriteCloser`.
func NewReadWriteCloser(rwc io.ReadWriteCloser) ReadWriteCloser {
return &readWriteCloser{rwc: rwc, socket: 0}
}
func (rwc *readWriteCloser) ReadFrame(frame *Frame) error {
b := make([]byte, 256) // TODO(brutella) optimize size
n, err := rwc.Read(b)
if err != nil {
return err
}
err = Unmarshal(b[:n], frame)
return err
}
func (rwc *readWriteCloser) WriteFrame(frame Frame) error {
b, err := Marshal(frame)
if err != nil {
return err
}
_, err = rwc.Write(b)
return err
}
func (rwc *readWriteCloser) Read(b []byte) (n int, err error) {
return rwc.rwc.Read(b)
}
func (rwc *readWriteCloser) Write(b []byte) (n int, err error) {
return rwc.rwc.Write(b)
}
func (rwc *readWriteCloser) Close() error {
rwc.socket = 0
return rwc.rwc.Close()
}
const (
solCANRaw = 101 // filter level for setsockopt call
canRawFilter = 1 // filter option for setsockopt call
)
// ErrorKernelFilterNotSupported is returned if the socket attribute is 0. Then the method
// setsockopt can't be called.
var ErrorKernelFilterNotSupported = errors.New("Not possible to set kernel filter.")
func (rwc *readWriteCloser) setFilter(filter []unix.CanFilter) error {
if rwc.socket == 0 {
return ErrorKernelFilterNotSupported
}
return unix.SetsockoptCanRawFilter(rwc.socket, solCANRaw, canRawFilter, filter)
}
func (rwc *readWriteCloser) deleteFilter() error {
if rwc.socket == 0 {
return ErrorKernelFilterNotSupported
}
return unix.SetsockoptCanRawFilter(rwc.socket, solCANRaw, canRawFilter, nil)
}