FindFirstChangeNotification locks parent folder

问题

I'm using FindFirstChangeNotification()/ReadDirectoryChangesW() to watch a folder for changes. It's working as expected. My Question is: When I try to rename the parent of the Watched folder, I get access denied, error 5. I'm guessing my FCN handle has the folder open for notification monitoring and changing the parent is not allowed.

Is there any way to monitor a subdirectory, say c:\folder\subfolder\anotherfolder\ and still be able to open a command prompt (or other program) and execute a "rename c:\folder\ c:\folder2"

here's my code snippet

    //
    // Sign up for notifications on the object. 
    //
    m_bWatchSubTree = TRUE;
    m_dwWatchFlags =
        FILE_NOTIFY_CHANGE_SECURITY |       // (0x100) change to security descriptor (NTFSACL?)
        FILE_NOTIFY_CHANGE_CREATION |       // (0x40) change to creation date
        FILE_NOTIFY_CHANGE_LAST_ACCESS |    // (0x20) change to last access date  
        FILE_NOTIFY_CHANGE_LAST_WRITE |     // (0x10) any change to the modification date/time of file in the folder
        FILE_NOTIFY_CHANGE_SIZE |           // (0x08) Size changed
        FILE_NOTIFY_CHANGE_ATTRIBUTES |     // (0x04) Atributes of something changed
        FILE_NOTIFY_CHANGE_DIR_NAME |       // (0x02) DIR name change in watched folder rename,create,delete FOLDER
        FILE_NOTIFY_CHANGE_FILE_NAME;       // (0x01) FILE name change in watched folder. rename,create,delete FILE

    CString strObjectPathAndName(_T("c:\\folder\\subfolder\\anotherfolder\\");
    m_hChangeHandle = ::FindFirstChangeNotification(strObjectPathAndName, m_bWatchSubTree, m_dwWatchFlags);
    if (m_hChangeHandle != INVALID_HANDLE_VALUE)
    {
        DWORD dwStatus = ::WaitForSingleObject(m_hChangeHandle, INFINITE);
        HANDLE  hDir = ::CreateFile(strObjectPathAndName, 
                                FILE_LIST_DIRECTORY,
                                FILE_SHARE_READ | FILE_SHARE_WRITE| FILE_SHARE_DELETE,
                                NULL, //security attributes
                                OPEN_EXISTING,
                                FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OVERLAPPED,          
                                NULL);
        DWORD dwBytesReturned = 0;
        FILE_NOTIFY_INFORMATION *p = (FILE_NOTIFY_INFORMATION*)nb.GetBuffer();
        if (::ReadDirectoryChangesW(hDir, p, nb.GetMaxSize(), m_bWatchSubTree, m_dwWatchFlags, &dwBytesReturned, NULL, NULL))
        {
        //
        // do some stuff
        }
    }

回答1:

Not sure if that's what you need,

If you are interested in listening to ANOTHER path while maintaining your current listener in c:\folder\subfolder\anotherfolder\, you will need an array of HANDLE types.

In your code it will look like this:

HANDLE m_hChangeHandle[x];// int x should be the quantity of your desired listeners.

Of course you need to use FindFirstChangeNotification for each of your array, ie:

m_hChangeHandle[0] = FindFirstChangeNotification(..., ..., ...);
m_hChangeHandle[1] = FindFirstChangeNotification(..., ..., ...);
//and so on..

Since you are using now more then 1 listener you can't keep using WaitForSingleObject but rather WaitForMultipleObjects. i.e:

WaitForMultipleObjects(x, m_hChangeHandle, FALSE, INFINITE);//False will wait for a change in at least one of the listeners.

Hope it's what you needed.

来源：https://stackoverflow.com/questions/27962294/findfirstchangenotification-locks-parent-folder

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c++

visual-c++

change-notification