From 9f08d874b6b3081d8708b884e6082397eb02f872 Mon Sep 17 00:00:00 2001
From: Marcus Tillmanns <marcus.tillmanns@qt.io>
Date: Mon, 14 Oct 2024 15:10:49 +0200
Subject: [PATCH] CmdBridge: Fix deadlock

The watch mutex was held indefinitely since the "defer" is only
called once the parent function exits. Moving the event handling
into its own function solves the issue.

Also removed unused function "processRemove"

Change-Id: I66598d1ba0fb66622ca97531f9ee13272ce63f50
Reviewed-by: hjk <hjk@qt.io>
---
 src/libs/gocmdbridge/server/watcher.go | 84 ++++++++++----------------
 1 file changed, 31 insertions(+), 53 deletions(-)

diff --git a/src/libs/gocmdbridge/server/watcher.go b/src/libs/gocmdbridge/server/watcher.go
index 251097da6cf..8d4f63c2d13 100644
--- a/src/libs/gocmdbridge/server/watcher.go
+++ b/src/libs/gocmdbridge/server/watcher.go
@@ -35,6 +35,36 @@ type watchevent struct {
 	EventType int
 }
 
+func handleEvent(event fsnotify.Event, watchHandler *WatcherHandler, out chan<- []byte) {
+	watchHandler.mutex.Lock()
+	defer watchHandler.mutex.Unlock()
+
+	// Find which watchList entries correspond to the event
+	for id, path := range watchHandler.watchList {
+		// See if the event path is a subpath of the watch path
+		if strings.HasPrefix(event.Name, path) {
+			data, _ := cbor.Marshal(watchevent{
+				Type:      "watchEvent",
+				Id:        id,
+				Path:      event.Name,
+				EventType: int(event.Op),
+			})
+			if event.Op == fsnotify.Remove && event.Name == path {
+				// Check if file exists
+				_, err := os.Stat(event.Name)
+				if err == nil {
+					// File exists, so lets add it again
+					err := watchHandler.watcher.Add(event.Name)
+					if err != nil {
+						sendError(out, command{Type: "watchEvent", Id: id}, err)
+					}
+				}
+			}
+			out <- data
+		}
+	}
+}
+
 func (watchHandler *WatcherHandler) start(out chan<- []byte) {
 	for {
 		select {
@@ -42,33 +72,7 @@ func (watchHandler *WatcherHandler) start(out chan<- []byte) {
 			if !ok {
 				return
 			}
-			watchHandler.mutex.Lock()
-			defer watchHandler.mutex.Unlock()
-
-			// Find which watchList entries correspond to the event
-			for id, path := range watchHandler.watchList {
-				// See if the event path is a subpath of the watch path
-				if strings.HasPrefix(event.Name, path) {
-					data, _ := cbor.Marshal(watchevent{
-						Type:      "watchEvent",
-						Id:        id,
-						Path:      event.Name,
-						EventType: int(event.Op),
-					})
-					if event.Op == fsnotify.Remove && event.Name == path {
-						// Check if file exists
-						_, err := os.Stat(event.Name)
-						if err == nil {
-							// File exists, so lets add it again
-							err := watchHandler.watcher.Add(event.Name)
-							if err != nil {
-								sendError(out, command{Type: "watchEvent", Id: id}, err)
-							}
-						}
-					}
-					out <- data
-				}
-			}
+			handleEvent(event, watchHandler, out)
 		case err, ok := <-watchHandler.watcher.Errors:
 			if !ok {
 				return
@@ -151,29 +155,3 @@ type watchnotfounderror struct {
 func (e *watchnotfounderror) Error() string {
 	return "Watch not found"
 }
-
-func (watchHandler *WatcherHandler) processRemove(cmd command, out chan<- []byte) {
-	watchHandler.mutex.Lock()
-	defer watchHandler.mutex.Unlock()
-
-	if _, ok := watchHandler.watchList[cmd.Id]; !ok {
-		sendError(out, cmd, &watchnotfounderror{})
-		return
-	}
-	watchHandler.watchRefs[cmd.Path]--
-	if watchHandler.watchRefs[cmd.Path] == 0 {
-		err := watchHandler.watcher.Remove(cmd.Path)
-		if err != nil {
-			sendError(out, cmd, err)
-			return
-		}
-	}
-	delete(watchHandler.watchList, cmd.Id)
-
-	data, _ := cbor.Marshal(removewatchresult{
-		Type:   "removewatchresult",
-		Id:     cmd.Id,
-		Result: true,
-	})
-	out <- data
-}