func()

in inotify/inotify_linux.go [139:204]

• 48 lines of code
• 11 McCabe index (conditional complexity)

func (w *Watcher) readEvents() {
	var buf [syscall.SizeofInotifyEvent * 4096]byte

	for {
		n, err := syscall.Read(w.fd, buf[:])
		// See if there is a message on the "done" channel
		var done bool
		select {
		case done = <-w.done:
		default:
		}

		// If EOF or a "done" message is received
		if n == 0 || done {
			// The syscall.Close can be slow.  Close
			// w.Event first.
			close(w.Event)
			err := syscall.Close(w.fd)
			if err != nil {
				w.Error <- os.NewSyscallError("close", err)
			}
			close(w.Error)
			return
		}
		if n < 0 {
			w.Error <- os.NewSyscallError("read", err)
			continue
		}
		if n < syscall.SizeofInotifyEvent {
			w.Error <- errors.New("inotify: short read in readEvents()")
			continue
		}

		var offset uint32
		// We don't know how many events we just read into the buffer
		// While the offset points to at least one whole event...
		for offset <= uint32(n-syscall.SizeofInotifyEvent) {
			// Point "raw" to the event in the buffer
			raw := (*syscall.InotifyEvent)(unsafe.Pointer(&buf[offset]))
			event := new(Event)
			event.Mask = uint32(raw.Mask)
			event.Cookie = uint32(raw.Cookie)
			nameLen := uint32(raw.Len)
			// If the event happened to the watched directory or the watched file, the kernel
			// doesn't append the filename to the event, but we would like to always fill the
			// the "Name" field with a valid filename. We retrieve the path of the watch from
			// the "paths" map.
			w.mu.Lock()
			name, ok := w.paths[int(raw.Wd)]
			w.mu.Unlock()
			if ok {
				event.Name = name
				if nameLen > 0 {
					// Point "bytes" at the first byte of the filename
					bytes := (*[syscall.PathMax]byte)(unsafe.Pointer(&buf[offset+syscall.SizeofInotifyEvent]))
					// The filename is padded with NUL bytes. TrimRight() gets rid of those.
					event.Name += "/" + strings.TrimRight(string(bytes[0:nameLen]), "\000")
				}
				// Send the event on the events channel
				w.Event <- event
			}
			// Move to the next event in the buffer
			offset += syscall.SizeofInotifyEvent + nameLen
		}
	}
}