From de179ddfafbff1a2e4f249b43b08c09ff1c67aab Mon Sep 17 00:00:00 2001
From: fabiankramm <fab.kramm@googlemail.com>
Date: Mon, 19 Jul 2021 14:39:28 +0200
Subject: [PATCH] fix: prevent recursive unwatch if watchpoints left

---
 notify_test.go    | 50 +++++++++++++++++++++++++++++++++++++++++++++++
 tree_recursive.go | 13 +++++++-----
 2 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/notify_test.go b/notify_test.go
index 330f75f..a4cd39d 100644
--- a/notify_test.go
+++ b/notify_test.go
@@ -147,6 +147,56 @@ func TestRenameInRoot(t *testing.T) {
 	}
 }
 
+func mustWatch(t *testing.T, path string) chan EventInfo {
+	c := make(chan EventInfo, 1)
+	err := Watch(path+"...", c, All)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return c
+}
+
+func TestStopChild(t *testing.T) {
+	tmpDir, err := ioutil.TempDir("", "notify_test-")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	// create test dir
+	err = os.MkdirAll(filepath.Join(tmpDir, "a/b/c"), 0755)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// watch a child and parent path across multiple channels.
+	// this can happen in any order.
+	ch1 := mustWatch(t, filepath.Join(tmpDir, "a"))
+	ch2 := mustWatch(t, filepath.Join(tmpDir, "a/b/c"))
+
+	// this leads to tmpDir/a being unwatched
+	Stop(ch2)
+
+	// fire an event that will never show up because the watchpoint for ./a is removed
+	// as well.
+	filePath := filepath.Join(tmpDir, "a/b/c/d")
+	go func() { _ = ioutil.WriteFile(filePath, []byte("X"), 0664) }()
+
+	timeout := time.After(5 * time.Second)
+	for {
+		select {
+		case ev := <-ch1:
+			t.Log(filePath, ev.Path(), ev.Event())
+			if ev.Path() == filePath && ev.Event() == Write {
+				return
+			}
+		case <-timeout:
+			t.Fatal("timed out before receiving event")
+		}
+	}
+}
+
 func TestRecreated(t *testing.T) {
 	tmpDir, err := ioutil.TempDir("", "notify_test-")
 	if err != nil {
diff --git a/tree_recursive.go b/tree_recursive.go
index 7f00dfe..177ab05 100644
--- a/tree_recursive.go
+++ b/tree_recursive.go
@@ -306,6 +306,7 @@ func (t *recursiveTree) Watch(path string, c chan<- EventInfo, events ...Event)
 func (t *recursiveTree) Stop(c chan<- EventInfo) {
 	var err error
 	fn := func(nd node) (e error) {
+		isRecursive := watchIsRecursive(nd)
 		diff := watchDel(nd, c, all)
 		switch {
 		case diff == none && watchTotal(nd) == 0:
@@ -315,13 +316,15 @@ func (t *recursiveTree) Stop(c chan<- EventInfo) {
 		case diff == none:
 			// Removing c from nd does not require shrinking its eventset.
 		case diff[1] == 0:
-			if watchIsRecursive(nd) {
-				e = t.w.RecursiveUnwatch(nd.Name)
-			} else {
-				e = t.w.Unwatch(nd.Name)
+			if watchTotal(nd) == 0 {
+				if isRecursive {
+					e = t.w.RecursiveUnwatch(nd.Name)
+				} else {
+					e = t.w.Unwatch(nd.Name)
+				}
 			}
 		default:
-			if watchIsRecursive(nd) {
+			if isRecursive {
 				e = t.w.RecursiveRewatch(nd.Name, nd.Name, diff[0], diff[1])
 			} else {
 				e = t.w.Rewatch(nd.Name, diff[0], diff[1])