2017

Declare variable as close as possible to where they are needed. In this case this could just be:

zip_t *archive = zip_open(...);

same here.

We are not using the return value of std::bind(), are we? Is there a reason why we need the ugly Callback<void(double)>::func here?

The Entry objects need to be deleted. I think here we should do what libarchive does, i.e. delete them (later) in the destructor.

Remove m_abortOperation. The libzip plugin will run in another thread, we need to use QThread::currentThread()->isInterruptionRequested() instead of this boolean flag. Have a look at the libarchive plugin.

nullptr?

2017 :p

Either initialize all the member variables here on in the constructor initializer list.