Inotify file system watching for linux.

pkg/watcher/linux.go

@@ -0,0 +1,79 @@
+package watcher
+
+import (
+	"syscall"
+	"unsafe"
+
+	"github.com/pkg/errors"
+)
+
+const CrDelMask uint32 = syscall.IN_CREATE | syscall.IN_DELETE
+
+type FSWatcher struct {
+	fd     int
+	wds    []int
+	closed bool
+}
+
+func NewFSWatcher() (fsw *FSWatcher, err error) {
+	fsw = &FSWatcher{closed: false}
+
+	fsw.fd, err = syscall.InotifyInit()
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to initialise inotify watcher")
+	}
+
+	fsw.wds = make([]int, 0)
+
+	return nil, nil
+}
+
+func (fsw *FSWatcher) AddWatch(path string, mask uint32) error {
+	wd, err := syscall.InotifyAddWatch(fsw.fd, path, mask)
+	if err != nil {
+		return errors.Wrapf(err, "failed to set %s on watch", path)
+	}
+
+	fsw.wds = append(fsw.wds, wd)
+	syscall.Read(fsw.fd, nil)
+
+	return nil
+}
+
+// WatchForMask checking for events from mask and returns inotify mask to channel.
+func (fsw *FSWatcher) WatchForMask(fired chan uint32, mask uint32) {
+	buffer := make([]byte, syscall.SizeofInotifyEvent)
+	go func() {
+		for !fsw.closed {
+			n, err := syscall.Read(fsw.fd, buffer)
+			if err != nil {
+				break
+			}
+
+			if n < syscall.SizeofInotifyEvent {
+				continue
+			}
+
+			event := (*syscall.InotifyEvent)(unsafe.Pointer(&buffer[0]))
+			if event.Mask&mask > 0 {
+				fired <- event.Mask
+			}
+		}
+	}()
+}
+
+func (fsw *FSWatcher) Close() error {
+	for _, wd := range fsw.wds {
+		if _, err := syscall.InotifyRmWatch(fsw.fd, uint32(wd)); err != nil {
+			return err
+		}
+	}
+
+	if err := syscall.Close(fsw.fd); err != nil {
+		return err
+	}
+
+	fsw.closed = true
+
+	return nil
+}