FILE_ACTION_MODIFIED received if folder was added and if folder was removed + FILE_ACTION_MODIFIED not called at all if folder was renamed to different directory

Wallby 46 Reputation points

According to "[If] a file is renamed to a different directory the client will receive [FILE_ACTION_REMOVED] along with FILE_ACTION_MODIFIED." and "[If] a file is renamed to a different directory the client will receive [FILE_ACTION_MODIFIED] along with FILE_ACTION_REMOVED.".
However I called ReadDirectoryChangesW with FILE_NOTIFY_CHANGE_DIR_NAME and what I get is the following in the order written..

FILE_ACTION_ADDED + FILE_ACTION_MODIFIED for a folder that was added
FILE_ACTION_ADDED for the next folder that was added
FILE_ACTION_RENAMED_OLD_NAME then FILE_ACTION_RENAMED_NEW_NAME for a folder renamed but not to different directory
FILE_ACTION_REMOVED for a folder moved to different directory then FILE_ACTION_ADDED for that folder, but no FILE_ACTION_MODIFIED as is mentioned in the documentation
FILE_ACTION_REMOVED for a folder deleted
FILE_ACTION_REMOVED + FILE_ACTION_MODIFIED for the last folder deleted

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  1. Wallby 46 Reputation points

    Further testing.. if waiting till all messages arrived after each edit it seems that..
    .. FILE_ACTION_MODIFIED was sent twice (both w. a->FileName == the new directory) for the "folder [renaming] but not to different directory".
    .. FILE_ACTION_REMOVED and FILE_ACTION_ADDED consistently arrived simultanouesly in ordered pairs if a folder was "renamed to a different directory"
    .. if a folder was moved into a deeper folder.. FILE_ACTION_MODIFIED was sent twice for that deeper folder
    .. if a folder was moved intoa less deep folder.. FILE_ACTION_MODIFIED was never sent unlike as is claimed at

  2. Wallby 46 Reputation points

    More testing.. as I am using mingw where ReadDirectoryChangesExW isn't implemented I called CreateFileA twice and..
    .. supplied one HANDLE to ReadDirectoryChangesW w. only "file stuff"(i.e. dwNotifyFilter == FILE_NOTIFY_CHANGE_FILE_NAME | FILE_NOTIFY_CHANGE_LAST_WRITE)
    .. supplied the other HANDLE to ReadDirectoryChangesW w. only "folder stuff" (i.e. dwNotifyFilter == FILE_NOTIFY_CHANGE_DIR_NAME)

    Turns out that each of the two FILE_ACTION_MODIFIED were sent for the "file stuff HANDLE" though "FILE_NOTIFY_INFORMATION .FileName" was a foldername.

    I wouldn't expect FILE_NOTIFY_CHANGE_FILE_NAME to be the culprit as there is FILE_NOTIFY_CHANGE_DIR_NAME too thus it wouldn't make sense if "FILE_NAME" would "read change(s)" to folder(s) and "DIR_NAME" would "read change(s)" to file(s).
    I suspected that FILE_NOTIFY_CHANGE_LAST_WRITE for the folder as there is no "LAST_FILE_WRITE" nor "LAST_DIR_WRITE" and testing verified that this is indeed what causes both FILE_ACTION_MODIFIED actions.

    What's still odd..
    .. FILE_ACTION_MODIFIED was sent twice for one rename (for both actions .FileName was identical too)
    .. FILE_ACTION_MODIFIED was never send though "a file" was "renamed to a different directory" as is claimed here and thus detecting rename (different from add and then remove) to different directory is not possible.

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  3. Obaid Farooqi MSFT 591 Reputation points Microsoft Employee

    Hi @Wallby
    Unless we receive a network trace to see on what directory change notify was set, it is not possible to explain the behavior you are observing. In my experiments, I see that I receive one notification for one change notify. I only see multiple notifications when there are multiple change notification requests. Here are some frames to illustrate my point:

    There are three change notify requests in frames 88,90,94; two for parent directory and one for newdir
    I changed the name of a file inside newdir (frames 448, 449)
    I received three notifications, one for each change notify request in frames 451,452 and 453.
    Frame 451 corresponds to frame 94 (I received FILE_ACTION_RENAMED_OLD_NAME & FILE_ACTION_RENAMED_NEW_NAME)
    Frame 452 corresponds to frame 88 (I received FILE_ACTION_MODIFIED)
    Frame 453 corresponds to frame 90 (I received FILE_ACTION_MODIFIED)

    If you need the network trace, send me an email at dochelp at microsoft dot com.
    I have filed a bug against MS-FSCC in the light of the above observations.

    Please let me know if this does not answer your question.

    Obaid Farooqi -MSFT

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