watch: tweak dir change events

fixes #6485

Signed-off-by: Nick Santos <[email protected]>

internal/ospath/ospath.go

@@ -154,6 +154,15 @@ func IsDir(path string) bool {
 	return f.Mode().IsDir()
 }
 
+func IsDirLstat(path string) bool {
+	f, err := os.Lstat(path)
+	if err != nil {
+		return false
+	}
+
+	return f.Mode().IsDir()
+}
+
 func IsBrokenSymlink(path string) (bool, error) {
 	// Stat resolves symlinks, lstat does not.
 	// So if Stat reports IsNotExist, but Lstat does not,

internal/watch/notify_test.go

@@ -218,6 +218,23 @@ func TestWatchDirectoryAndTouchIt(t *testing.T) {
 	f.assertEvents()
 }
 
+func TestWatchDirectoryAndTouchSubdir(t *testing.T) {
+	f := newNotifyFixture(t)
+
+	cTime := time.Now()
+	root := f.TempDir("root")
+	path := filepath.Join(root, "change")
+	a := filepath.Join(path, "a.txt")
+	f.WriteFile(a, "a")
+
+	f.watch(root)
+	f.fsync()
+
+	err := os.Chtimes(path, cTime, time.Now())
+	assert.NoError(t, err)
+	f.assertEvents()
+}
+
 func TestWatchNonExistentPathDoesNotFireSiblingEvent(t *testing.T) {
 	f := newNotifyFixture(t)
 

internal/watch/watcher_naive.go

@@ -151,16 +151,32 @@ func (d *naiveNotify) loop() {
 		}
 
 		if e.Op&fsnotify.Create != fsnotify.Create {
-			if d.shouldNotify(e.Name) {
-				d.wrappedEvents <- FileEvent{e.Name}
+			if !d.shouldNotify(e.Name) {
+				continue
 			}
+
+			// Don't send events for directories when the modtime is being changed.
+			//
+			// This is a bit of a hack because every OS represents modtime updates
+			// a bit differently and they don't map well to fsnotify events.
+			//
+			// On Windows, updating the modtime of a directory is a fsnotify.Write.
+			// On Linux, it's a fsnotify.Chmod.
+			isDirUpdateOnly := (e.Op == fsnotify.Write || e.Op == fsnotify.Chmod) &&
+				ospath.IsDir(e.Name)
+			if isDirUpdateOnly {
+				continue
+			}
+
+			d.wrappedEvents <- FileEvent{e.Name}
 			continue
 		}
 
 		if d.isWatcherRecursive {
-			if d.shouldNotify(e.Name) {
-				d.wrappedEvents <- FileEvent{e.Name}
+			if !d.shouldNotify(e.Name) {
+				continue
 			}
+			d.wrappedEvents <- FileEvent{e.Name}
 			continue
 		}
 
@@ -223,8 +239,7 @@ func (d *naiveNotify) shouldNotify(path string) bool {
 
 	if _, ok := d.notifyList[path]; ok {
 		// We generally don't care when directories change at the root of an ADD
-		stat, err := os.Lstat(path)
-		isDir := err == nil && stat.IsDir()
+		isDir := ospath.IsDirLstat(path)
 		if isDir {
 			return false
 		}