Question

我试图使用FSEvent Api在mac中测试一个简单的filewatcher。我得到了事件的回调，一切似乎都有效但我无法恢复上下文结构的info字段中包含的信息。这是我的代码：

void feCallback(ConstFSEventStreamRef streamRef,
                   void* pClientCallBackInfo,
                   size_t numEvents,
                   void* pEventPaths,
                   const FSEventStreamEventFlags eventFlags[],
                   const FSEventStreamEventId eventIds[]);

Watcher::Watcher(const QString& pathToFolder) :
folderPath_(pathToFolder)
{
    CFStringCreateWithCString(kCFAllocatorDefault,path,kCFStringEncodingUTF8);
    NSString *directory = [[NSString stringWithUTF8String:folderPath_.toStdString().c_str()] stringByDeletingLastPathComponent];
    NSArray *pathToWatch = [NSArray arrayWithObjects:directory, nil];
    FSEventStreamContext context = {0, (void*)this, NULL, NULL, NULL}; //the second parameter is the 'user info' field

    CFAbsoluteTime latency = 3.0;
    FSEventStreamRef stream;
    stream = FSEventStreamCreate(NULL,
                             &feCallback,
                             &context,
                             (CFArrayRef)pathsToWatch,
                             kFSEventStreamEventIdSinceNow, 
                             latency,
                             kFSEventStreamCreateFlagFileEvents | kFSEventStreamCreateFlagNoDefer);
   if (!stream)
   {
       qDebug() << "Could not create event stream for path";
       return;
   }
   else
   {
       FSEventStreamScheduleWithRunLoop(stream, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
       FSEventStreamStart(stream);
       qDebug() << "stream created";
   }
}

QString Watcher::getFolderPath()
{
    return folderPath_;
}

void  feCallback(ConstFSEventStreamRef streamRef,
                   void* pClientCallBackInfo,
                   size_t numEvents,
                   void* pEventPaths,
                   const FSEventStreamEventFlags eventFlags[],
                   const FSEventStreamEventId eventIds[])
{
    Q_UNUSED(streamRef)
    Q_UNUSED(eventIds)

    qDebug() << ((Watcher*)pClientCallBackInfo)->getFolderPath();
}

我在回调中遇到sigsev错误。此外，如果我在上下文中插入一个int，例如：

int testInt = 4;
FSEventStreamContext context = {0, &testInt, NULL, NULL, NULL};

在回调中

qDebug() << *((int*)pClientCallBackInfo);

打印我-1

那么，我做错了什么？ Thx提前！

Answer 1

问题与此代码无关。指针工作正常，但他的对象丢失了。

FSEventStreamCreate回调中丢失的上下文指针（c ++）

1 个答案: