Qv2ray/src/runguard.cpp

#include <QCryptographicHash>

#include "runguard.h"

//from https://stackoverflow.com/a/28172162
namespace
{

    QString generateKeyHash( const QString& key, const QString& salt )
    {
        QByteArray data;
        data.append( key.toUtf8() );
        data.append( salt.toUtf8() );
        data = QCryptographicHash::hash( data, QCryptographicHash::Sha1 ).toHex();
        return data;
    }

}


RunGuard::RunGuard( const QString& key )
    : key( key )
    , memLockKey( generateKeyHash( key, "_memLockKey" ) )
    , sharedmemKey( generateKeyHash( key, "_sharedmemKey" ) )
    , sharedMem( sharedmemKey )
    , memLock( memLockKey, 1 )
{
    memLock.acquire();
    {
        QSharedMemory fix( sharedmemKey );    // Fix for *nix: http://habrahabr.ru/post/173281/
        fix.attach();
    }
    memLock.release();
}

RunGuard::~RunGuard()
{
    release();
}

bool RunGuard::isAnotherRunning()
{
    if ( sharedMem.isAttached() ) {
        return false;
    }
    memLock.acquire();
    const bool isRunning = sharedMem.attach();
    if ( isRunning ) {
        sharedMem.detach();
    }
    memLock.release();
    return isRunning;
}

bool RunGuard::isSingleInstance()
{
    if ( isAnotherRunning() ) { // Extra check
        return false;
    }
    memLock.acquire();
    const bool result = sharedMem.create( sizeof( quint64 ) );
    memLock.release();
    if ( !result ) {
        release();
        return false;
    }
    return true;
}

void RunGuard::release()
{
    memLock.acquire();
    if ( sharedMem.isAttached() ) {
        sharedMem.detach();
    }
    memLock.release();
}