Q188321: FindFirstChangeNotification May Not Notify All Processes

Article: Q188321
Product(s): Microsoft Windows NT
Version(s): WinNT:4.0
Operating System(s): 
Keyword(s): 
Last Modified: 09-AUG-2001

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The information in this article applies to:

- Microsoft Windows NT Workstation version 4.0 
- Microsoft Windows NT Server version 4.0 
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SYMPTOMS
========

The FindFirstChangeNotification call may not notify all processes that have sent
a notify request on the same directory. This may occur if the directory is on a
remote computer.

CAUSE
=====

This problem occurs because of an optimization in the redirector if multiple
processes open the same directory across the network. What the redirector may do
is only open one handle to the remote directory. This causes the notify request
to behave as though the notify requests were all sent to the same handle. By
design, only one request will be notified per directory change per handle.

RESOLUTION
==========

To receive multiple notify requests across the network, the user who runs the
program must have the "backup file and directories" user right. Then the program
must set the privilege using the AdjustTokenPrivileges call. This is because the
FindFirstChangeNotification API sets the FILE_OPEN_FOR_BACKUP_INTENT in its
create packet. This is to prevent the optimization mentioned above from
occurring. However, the "backup file and directories" privilege must be turned
on for it to work.
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Keywords          :  
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400
Version           : WinNT:4.0
Issue type        : kbprb

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