Qt way of knowing if a instance of my app is already running on my computer

[Momergil]

Hello!

I want my application to know, in the main(...) method preferentially even before starting the QApplication, if an instance of the same application is already running.

Till now I have being doing this by using the following method:

/*!
 * \brief getOthermShare tells if there is another mShare opened in this machine.
 * \return
 */
bool getOthermShare()
{
    bool mshare_detectado = false;
    // Get the list of process identifiers
    DWORD aProcesses[1024], cbNeeded, cProcesses;
 
    //Tenta 10 vezes capturar os processos; se nao conseguir, fecha (rever isso aqui!)
    for (int aaa = 0; aaa < 10; aaa++)
    {
        if (EnumProcesses( aProcesses, sizeof(aProcesses), &cbNeeded ) )
            break;
        else if (aaa == 9)
        {
            QMessageBox::warning(NULL,QMessageBox::tr("Error"),QMessageBox::tr("A fatal error ocurred. Please close down your application and try again.\nIf the problem persists, enter in contact with "
                                 "the support team."));
            return false;
        }
    }
 
    // Calculate how many process identifiers were returned.
    cProcesses = cbNeeded / sizeof(DWORD);
 
    // Discover the name and process identifier for each process.
    for (unsigned int i = 0; i < cProcesses; i++ )
    {
        if( aProcesses[i] != 0 )
        {
            TCHAR szProcessName[MAX_PATH] = TEXT("<unknown>");
 
            // Get a handle to the process.
            HANDLE hProcess = OpenProcess( PROCESS_QUERY_INFORMATION | PROCESS_ALL_ACCESS | READ_CONTROL |
                                           PROCESS_VM_READ,
                                           FALSE, aProcesses[i] );
 
            // Get the process name.
            if (NULL != hProcess )
            {
                HMODULE hMod;
                DWORD cbNeeded;
 
                if ( EnumProcessModules( hProcess, &hMod, sizeof(hMod),
                     &cbNeeded) )
                {
                    GetModuleBaseName( hProcess, hMod, szProcessName,
                                       sizeof(szProcessName)/sizeof(TCHAR) );
                }
 
#ifdef Q_OS_WIN
#ifdef UNICODE
 
                if (QString::fromUtf16((ushort*)szProcessName).section(".",0,0) == "mShare")
                {
                    if (!mshare_detectado)
                        mshare_detectado = true;
                    else
                    {
                        CloseHandle( hProcess );
                        return true;
                    }
                }
#endif
#endif
                // Release the handle to the process.
                CloseHandle( hProcess );
            }
        }
    }
 
    return false;
}

/*!
 * \brief getOthermShare tells if there is another mShare opened in this machine.
 * \return
 */
bool getOthermShare()
{
    bool mshare_detectado = false;
    // Get the list of process identifiers
    DWORD aProcesses[1024], cbNeeded, cProcesses;

    //Tenta 10 vezes capturar os processos; se nao conseguir, fecha (rever isso aqui!)
    for (int aaa = 0; aaa < 10; aaa++)
    {
        if (EnumProcesses( aProcesses, sizeof(aProcesses), &cbNeeded ) )
            break;
        else if (aaa == 9)
        {
            QMessageBox::warning(NULL,QMessageBox::tr("Error"),QMessageBox::tr("A fatal error ocurred. Please close down your application and try again.\nIf the problem persists, enter in contact with "
                                 "the support team."));
            return false;
        }
    }

    // Calculate how many process identifiers were returned.
    cProcesses = cbNeeded / sizeof(DWORD);

    // Discover the name and process identifier for each process.
    for (unsigned int i = 0; i < cProcesses; i++ )
    {
        if( aProcesses[i] != 0 )
        {
            TCHAR szProcessName[MAX_PATH] = TEXT("<unknown>");

            // Get a handle to the process.
            HANDLE hProcess = OpenProcess( PROCESS_QUERY_INFORMATION | PROCESS_ALL_ACCESS | READ_CONTROL |
                                           PROCESS_VM_READ,
                                           FALSE, aProcesses[i] );

            // Get the process name.
            if (NULL != hProcess )
            {
                HMODULE hMod;
                DWORD cbNeeded;

                if ( EnumProcessModules( hProcess, &hMod, sizeof(hMod),
                     &cbNeeded) )
                {
                    GetModuleBaseName( hProcess, hMod, szProcessName,
                                       sizeof(szProcessName)/sizeof(TCHAR) );
                }

#ifdef Q_OS_WIN
#ifdef UNICODE

                if (QString::fromUtf16((ushort*)szProcessName).section(".",0,0) == "mShare")
                {
                    if (!mshare_detectado)
                        mshare_detectado = true;
                    else
                    {
                        CloseHandle( hProcess );
                        return true;
                    }
                }
#endif
#endif
                // Release the handle to the process.
                CloseHandle( hProcess );
            }
        }
    }

    return false;
}

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which obviously have two problems: first, it works only for Windows, and second, its kinda akward :P

So I'ld like to know if there is a "Qt way" of doing the same thing with the advantage of being platform independent. I noticed the solution shown at [http://www.qtcentre.org/wiki/index.p...leApplication], but I must say I didn't like that way :P Is there another solution? (and one that don't use anything extern to the application, such as a file that is written with "1" when the software is opened or the like)


Thanks,

Momergil

[stampede]

Take a look at this article : http://developer.nokia.com/community...Qt_application
Its 4 years old, but solutions with local socket and shared memory should work just fine.