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c++winapiusbmedia-player

Obtaining directory change notifications for media portable devices

We can find the change in directory by using the FindFirstChangeNotification() and FindNextChangeNotification() functions like :

FindFirstChangeNotification( 
      lpDir,                         // directory to watch 
      FALSE,                         // do not watch subtree 
      FILE_NOTIFY_CHANGE_FILE_NAME); // watch file name changes

But in Windows there is no actual path for media portable devices like Android phones, camera, etc. Then how can we track the changes (create,copy,delete,rename) done on these devices in C++?

Solution

  • These media devices only exist at the shell level, they do not allow direct access to their filesystem (and even if they did, it might be ext3 or some other filesystem not supported by Windows). You cannot use FindFirstChangeNotification and other functions in kernel32, you must use the functions in shell32 and shlwapi that supports IShellItem, IShellFolder and PIDLs.

    To create a PIDL you can call SHParseDisplayName if you know the path (shell:::{something}\{something}) or SHGetDesktopFolder + IShellFolder::EnumObjects to walk the entire shell namespace.

    Sometimes it is possible to find the shell: path by right clicking the item in the Explorer breadcrumb-bar and selecting "Copy address".

    When you have an absolute PIDL to the device folder you can call SHChangeNotifyRegister.