func()

in pkg/kprobe/kprobe.go [159:233]
58 lines of code
10 McCabe index (conditional complexity)

func (k *bpfKprobe) KretprobeAttach() error {

	if k.progFD <= 0 {
		log.Infof("invalid BPF prog FD %d", k.progFD)
		return fmt.Errorf("Invalid BPF prog FD %d", k.progFD)

	}
	// if event is nil, we pick funcName
	if len(k.eventName) == 0 {
		k.eventName = k.funcName
	}

	// Register the Kprobe event
	file, err := os.OpenFile(constdef.KPROBE_SYS_EVENTS, os.O_WRONLY|os.O_APPEND, 0)
	if err != nil {
		log.Errorf("error opening kprobe_events file: %v", err)
		return err
	}
	defer file.Close()

	eventString := fmt.Sprintf("r4096:kretprobes/%s %s", k.eventName, k.funcName)
	_, err = file.WriteString(eventString)
	if err != nil {
		log.Errorf("error writing to kprobe_events file: %v", err)
		return err
	}

	//Get the Kprobe ID
	kprobeIDpath := fmt.Sprintf("%s/%s/id", constdef.KRETPROBE_SYS_DEBUG, k.eventName)
	data, err := os.ReadFile(kprobeIDpath)
	if err != nil {
		log.Errorf("unable to read the kretprobeID: %v", err)
		return err
	}
	id := strings.TrimSpace(string(data))
	eventID, err := strconv.Atoi(id)
	if err != nil {
		log.Errorf("invalid ID during parsing: %s - %w", id, err)
		return err
	}

	log.Infof("Got eventID %d", eventID)

	attr := unix.PerfEventAttr{
		Type:   unix.PERF_TYPE_TRACEPOINT,
		Sample: 1,
		Wakeup: 1,
		Config: uint64(eventID),
	}
	attr.Size = uint32(unsafe.Sizeof(attr))

	fd, err := unix.PerfEventOpen(&attr, -1, 0, -1, unix.PERF_FLAG_FD_CLOEXEC)
	if err != nil {
		log.Errorf("failed to open perf event %v", err)
		return err
	}

	log.Infof("Attach bpf program to perf event Prog FD %d Event FD %d", k.progFD, fd)

	if _, _, err := unix.Syscall(unix.SYS_IOCTL, uintptr(int(fd)), uintptr(uint(unix.PERF_EVENT_IOC_SET_BPF)), uintptr(k.progFD)); err != 0 {
		log.Errorf("error attaching bpf program to perf event: %v", err)
		return err
	}

	if _, _, err := unix.Syscall(unix.SYS_IOCTL, uintptr(int(fd)), uintptr(uint(unix.PERF_EVENT_IOC_ENABLE)), 0); err != 0 {
		log.Errorf("error enabling perf event: %v", err)
		return err
	}

	k.SetPerfFD(fd)

	log.Infof("KRETPROBE Attach done!!! %d", fd)
	return nil

}