449 lines
12 KiB
C++
449 lines
12 KiB
C++
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//*************************************************************
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//
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// Group Policy Notification
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//
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// Microsoft Confidential
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// Copyright (c) Microsoft Corporation 1997-1998
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// All rights reserved
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//
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// Notes: There is a small window where notifications
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// can be lost. If while processing an eMonitor workitem
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// a policy event is Pulsed then that notification will
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// be lost. This window can be closed by using two threads.
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//
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// History: 28-Sep-98 SitaramR Created
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//
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//*************************************************************
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#include "gphdr.h"
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//
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// Work items for notification thread
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//
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enum EWorkType { eMonitor, // Monitor events
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eTerminate }; // Stop monitoring
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//
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// Entry in list of registered events
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//
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typedef struct _GPNOTIFINFO
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{
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HANDLE hEvent; // Event to be signaled
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BOOL bMachine; // Machine policy notifcation ?
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struct _GPNOTIFINFO * pNext; // Singly linked list ptr
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} GPNOTIFINFO;
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typedef struct _GPNOTIFICATION
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{
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HANDLE hThread; // Notification thread
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HANDLE hThreadEvent; // For signaling notification thread (Ordering of fields is important)
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HANDLE hMachEvent; // Event signaled by machine policy change
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HANDLE hUserEvent; // Event signaled by user policy change
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enum EWorkType eWorkType; // Work descrpition for notification thread
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GPNOTIFINFO * pNotifList; // List of registered events
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} GPNOTIFICATION;
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GPNOTIFICATION g_Notif = { NULL,
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NULL,
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NULL,
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NULL,
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eMonitor,
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NULL };
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CRITICAL_SECTION g_NotifyCS; // Lock
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//
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// Forward decls
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//
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DWORD WINAPI NotificationThread();
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void NotifyEvents( BOOL bMachine );
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//*************************************************************
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//
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// InitNotifSupport, ShutdownNotifSupport
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//
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// Purpose: Initialization and cleanup routines
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//
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//*************************************************************
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void InitializeNotifySupport()
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{
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InitializeCriticalSection( &g_NotifyCS );
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}
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void ShutdownNotifySupport()
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{
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BOOL fWait = FALSE;
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DWORD dwResult;
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{
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EnterCriticalSection( &g_NotifyCS );
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if ( g_Notif.hThread != NULL )
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{
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//
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// Set up terminate workitem and then signal thread
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//
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fWait = TRUE;
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g_Notif.eWorkType = eTerminate;
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SetEvent( g_Notif.hThreadEvent );
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}
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LeaveCriticalSection( &g_NotifyCS );
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}
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if ( fWait )
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WaitForSingleObject( g_Notif.hThread, INFINITE );
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{
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EnterCriticalSection( &g_NotifyCS );
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//
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// Close all opened handles
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//
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if ( g_Notif.hThread != NULL )
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CloseHandle( g_Notif.hThread );
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if ( g_Notif.hThreadEvent != NULL )
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CloseHandle( g_Notif.hThreadEvent );
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if ( g_Notif.hUserEvent != NULL )
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CloseHandle( g_Notif.hUserEvent );
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if ( g_Notif.hMachEvent != NULL )
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CloseHandle( g_Notif.hMachEvent );
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LeaveCriticalSection( &g_NotifyCS );
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}
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DeleteCriticalSection( &g_NotifyCS );
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}
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//*************************************************************
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//
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// RegisterGPNotification
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//
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// Purpose: Registers for a group policy change notification
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//
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// Parameters: hEvent - Event to be notified
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// bMachine - If true, then register for
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// machine policy notification, else
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// user policy notification
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//
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// Returns: True if successful
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// False if error occurs
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//
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//*************************************************************
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BOOL WINAPI RegisterGPNotification( IN HANDLE hEvent, IN BOOL bMachine )
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{
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BOOL bResult = FALSE;
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BOOL bNotifyThread = FALSE;
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GPNOTIFINFO *pNotifInfo = NULL;
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EnterCriticalSection( &g_NotifyCS );
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//
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// Create events and thread as needed
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//
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if ( g_Notif.hThreadEvent == NULL )
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{
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g_Notif.hThreadEvent = CreateEvent( NULL, TRUE, FALSE, NULL );
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if ( g_Notif.hThreadEvent == NULL )
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goto Exit;
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}
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if ( g_Notif.hMachEvent == NULL )
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{
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g_Notif.hMachEvent = OpenEvent (SYNCHRONIZE, FALSE, MACHINE_POLICY_APPLIED_EVENT);
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if ( g_Notif.hMachEvent == NULL ) {
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DebugMsg((DM_WARNING, TEXT("RegisterGPNotification: CreateEvent failed with %d"),
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GetLastError()));
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goto Exit;
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}
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bNotifyThread = TRUE;
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}
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if ( !bMachine && g_Notif.hUserEvent == NULL )
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{
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g_Notif.hUserEvent = OpenEvent (SYNCHRONIZE, FALSE, USER_POLICY_APPLIED_EVENT);
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if ( g_Notif.hUserEvent == NULL ) {
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DebugMsg((DM_WARNING, TEXT("RegisterGPNotification: CreateEvent failed with %d"),
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GetLastError()));
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goto Exit;
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}
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bNotifyThread = TRUE;
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}
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if ( g_Notif.hThread == NULL )
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{
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DWORD dwThreadId;
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g_Notif.hThread = CreateThread( NULL,
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0,
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(LPTHREAD_START_ROUTINE) NotificationThread,
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0,
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0,
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&dwThreadId );
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if ( g_Notif.hThread == NULL ) {
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DebugMsg((DM_WARNING, TEXT("RegisterGPNotification: CreateThread failed with %d"),
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GetLastError()));
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goto Exit;
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}
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bNotifyThread = TRUE;
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}
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if ( bNotifyThread )
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{
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//
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// Notify thread that there is a new workitem, possibly
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// user event has been added.
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//
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g_Notif.eWorkType = eMonitor;
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SetEvent( g_Notif.hThreadEvent );
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}
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//
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// Add event to beginning of list
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//
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pNotifInfo = (GPNOTIFINFO *) LocalAlloc( LPTR, sizeof(GPNOTIFINFO) );
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if ( pNotifInfo == NULL ) {
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DebugMsg((DM_WARNING, TEXT("RegisterGPNotification: LocalAlloc failed with %d"),
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GetLastError()));
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goto Exit;
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}
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pNotifInfo->hEvent = hEvent;
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pNotifInfo->bMachine = bMachine;
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pNotifInfo->pNext = g_Notif.pNotifList;
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g_Notif.pNotifList = pNotifInfo;
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bResult = TRUE;
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Exit:
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LeaveCriticalSection( &g_NotifyCS );
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return bResult;
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}
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//*************************************************************
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//
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// UnregisterGPNotification
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//
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// Purpose: Removes registration for a group policy change notification
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//
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// Parameters: hEvent - Event to be removed
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//
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// Return: True if successful
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// False if error occurs
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//
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//*************************************************************
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BOOL WINAPI UnregisterGPNotification( IN HANDLE hEvent )
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{
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BOOL bFound = FALSE;
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GPNOTIFINFO *pTrailPtr = NULL;
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GPNOTIFINFO *pCurPtr = NULL;
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EnterCriticalSection( &g_NotifyCS );
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pCurPtr = g_Notif.pNotifList;
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while ( pCurPtr != NULL )
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{
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if ( pCurPtr->hEvent == hEvent )
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{
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//
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// Found match, so delete entry
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//
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if ( pTrailPtr == NULL )
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{
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//
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// First elem of list matched
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//
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g_Notif.pNotifList = pCurPtr->pNext;
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}
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else
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pTrailPtr->pNext = pCurPtr->pNext;
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LocalFree( pCurPtr );
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bFound = TRUE;
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break;
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}
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//
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// Advance down the list
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//
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pTrailPtr = pCurPtr;
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pCurPtr = pCurPtr->pNext;
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}
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LeaveCriticalSection( &g_NotifyCS );
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return bFound;
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}
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//*************************************************************
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//
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// CGPNotification::NotificationThread
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//
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// Purpose: Separate thread for notifications
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//
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// Returns: 0
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//
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//*************************************************************
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DWORD WINAPI NotificationThread()
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{
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DWORD cEvents = 2;
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BOOL fShutdown = FALSE;
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HINSTANCE hInst = LoadLibrary (TEXT("userenv.dll"));
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{
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EnterCriticalSection( &g_NotifyCS );
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//
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// The event fields in g_Notif are ordered as hThreadEvent,
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// hMachEvent and finally hUserEvent. The first two events have
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// to be successfully created in order for this thread to run
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// (see asserts). If the user event has been successfully created
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// then that too is monitored.
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//
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DmAssert( g_Notif.hThreadEvent != NULL && g_Notif.hMachEvent != NULL );
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if ( g_Notif.hUserEvent != NULL )
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cEvents = 3;
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LeaveCriticalSection( &g_NotifyCS );
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}
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while ( !fShutdown )
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{
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DWORD dwResult = WaitForMultipleObjects( cEvents,
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&g_Notif.hThreadEvent,
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FALSE,
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INFINITE );
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EnterCriticalSection( &g_NotifyCS );
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if ( dwResult == WAIT_FAILED )
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{
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DebugMsg((DM_WARNING, TEXT("GPNotification: WaitforMultipleObjects failed")));
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fShutdown = TRUE;
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}
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else if ( dwResult == WAIT_OBJECT_0 )
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{
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ResetEvent( g_Notif.hThreadEvent );
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if ( g_Notif.eWorkType == eMonitor )
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{
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//
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// Start monitoring user events too
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//
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if ( g_Notif.hUserEvent != NULL )
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cEvents = 3;
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}
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else
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fShutdown = TRUE;
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}
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else if ( dwResult == WAIT_OBJECT_0 + 1 || dwResult == WAIT_OBJECT_0 + 2 )
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{
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BOOL bMachine = (dwResult == WAIT_OBJECT_0 + 1);
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NotifyEvents( bMachine );
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if ( g_Notif.pNotifList == NULL )
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fShutdown = TRUE;
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}
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else
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{
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if ( dwResult == WAIT_ABANDONED_0 || dwResult == WAIT_ABANDONED_0 + 1 )
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fShutdown = TRUE;
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else
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{
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CloseHandle( g_Notif.hUserEvent );
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g_Notif.hUserEvent = NULL;
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cEvents = 2;
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}
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}
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if ( fShutdown )
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{
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//
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// Close all handles and thread
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//
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CloseHandle( g_Notif.hThreadEvent );
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g_Notif.hThreadEvent = NULL;
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if ( g_Notif.hMachEvent != NULL )
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{
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CloseHandle( g_Notif.hMachEvent );
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g_Notif.hMachEvent = NULL;
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}
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if ( g_Notif.hUserEvent != NULL )
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{
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CloseHandle( g_Notif.hUserEvent );
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g_Notif.hUserEvent = NULL;
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}
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CloseHandle( g_Notif.hThread );
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g_Notif.hThread = NULL;
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}
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LeaveCriticalSection( &g_NotifyCS );
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}
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if ( hInst != NULL )
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FreeLibraryAndExitThread (hInst, 0);
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return 0;
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}
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//*************************************************************
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//
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// NotifyEvents
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//
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// Purpose: Notifies registered events
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||
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//
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// Parameters: bMachine - Is this a machine policy change ?
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//
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||
|
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//*************************************************************
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||
|
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||
|
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void NotifyEvents( BOOL bMachine )
|
||
|
|
{
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||
|
|
GPNOTIFINFO *pNotifInfo = NULL;
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||
|
|
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||
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pNotifInfo = g_Notif.pNotifList;
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||
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|
while ( pNotifInfo != NULL )
|
||
|
|
{
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||
|
|
if ( pNotifInfo->bMachine == bMachine )
|
||
|
|
{
|
||
|
|
SetEvent( pNotifInfo->hEvent );
|
||
|
|
}
|
||
|
|
|
||
|
|
pNotifInfo = pNotifInfo->pNext;
|
||
|
|
}
|
||
|
|
}
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