vendor: github.com/moby/buildkit 6bd81372ad6f (master)

- tests: implement NetNSDetached method

full diff: 6e200afad5...6bd81372ad

Co-authored-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor/github.com/moby/buildkit/util/progress/multiwriter.go

@@ -36,6 +36,15 @@ func (ps *MultiWriter) Add(pw Writer) {
 	if !ok {
 		return
 	}
+	if pws, ok := rw.(*MultiWriter); ok {
+		if pws.contains(ps) {
+			// this would cause a deadlock, so we should panic instead
+			// NOTE: this can be caused by a cycle in the scheduler states,
+			// which is created by a series of unfortunate edge merges
+			panic("multiwriter loop detected")
+		}
+	}
+
 	ps.mu.Lock()
 	plist := make([]*Progress, 0, len(ps.items))
 	plist = append(plist, ps.items...)
@@ -102,3 +111,24 @@ func (ps *MultiWriter) writeRawProgress(p *Progress) error {
 func (ps *MultiWriter) Close() error {
 	return nil
 }
+
+func (ps *MultiWriter) contains(pw rawProgressWriter) bool {
+	ps.mu.Lock()
+	defer ps.mu.Unlock()
+	_, ok := ps.writers[pw]
+	if ok {
+		return true
+	}
+
+	for w := range ps.writers {
+		w, ok := w.(*MultiWriter)
+		if !ok {
+			continue
+		}
+		if w.contains(pw) {
+			return true
+		}
+	}
+
+	return false
+}