95 lines
2.4 KiB
C++
95 lines
2.4 KiB
C++
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// Copyright (C) 1999 AT&T Laboratories Cambridge. All Rights Reserved.
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//
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// This file is part of the VNC system.
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//
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// The VNC system is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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// USA.
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//
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// TightVNC distribution homepage on the Web: http://www.tightvnc.com/
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//
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// If the source code for the VNC system is not available from the place
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// whence you received this file, check http://www.uk.research.att.com/vnc or contact
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// the authors on vnc@uk.research.att.com for information on obtaining it.
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// vncInstHandler.cpp
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// Implementation of the class used to ensure that only
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// one instance is running
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#include "stdhdrs.h"
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#include "vncInstHandler.h"
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// Name of the mutex
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#ifdef HORIZONLIVE
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const char mutexname [] = "AppShareHost_Instance_Mutex";
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#else
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const char mutexname [] = "WinVNC_Win32_Instance_Mutex";
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#endif
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// The class methods
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vncInstHandler::vncInstHandler() : m_mutex(NULL)
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{
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}
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vncInstHandler::~vncInstHandler()
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{
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// make sure mutex is cleared as we exit
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Release();
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}
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BOOL
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vncInstHandler::Init()
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{
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// Create the named mutex
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m_mutex = CreateMutex(NULL, FALSE, mutexname);
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if (m_mutex == NULL)
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return FALSE;
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// Check that the mutex didn't already exist
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if (GetLastError() == ERROR_ALREADY_EXISTS)
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return FALSE;
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return TRUE;
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}
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//
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// allow mutex to be explicitely cleared
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//
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DWORD
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vncInstHandler::Release()
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{
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//
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// CloseHandle() will throw an exception when
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// passed an invalid handle
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//
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try
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{
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CloseHandle(m_mutex);
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}
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catch (...)
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{
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//
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// Release() should be called once from the user code,
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// and a second time by the object's destructor.
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// the second call will cause an exception.
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// we can just ignore it.
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//
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}
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return GetLastError();
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}
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