playlists: deny negative durations

store/playlists.go

@@ -43,6 +43,9 @@ func (p *Playlist) BeforeSave(tx *gorm.DB) error {
 	hasEntryWithoutDuration := false
 	for idx := range p.Entries {
 		p.Entries[idx].LineNum = uint(idx)
+		if p.Entries[idx].Duration != nil && *(p.Entries[idx].Duration) < 0 {
+			return ErrInvalidPlaylistEntry{idx, "negative durations are not allowed"}
+		}
 
 		if p.Entries[idx].File != nil {
 			if p.Entries[idx].File.ShowName == "" {