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#include <cstdlib>
#include <QtCore/QSharedMemory>
#include <QtCore/QMutex>
#include <QtNetwork/QLocalSocket>
#include <QtNetwork/QLocalServer>
#ifdef Q_OS_UNIX
#include <signal.h>
#include <unistd.h>
#endif
#include "singleapplication.h"
class SingleApplicationPrivate {
Q_DECLARE_PUBLIC(SingleApplication)
public:
SingleApplicationPrivate(SingleApplication *q_ptr) : q_ptr(q_ptr) { }
void startServer(QString &serverName)
{
Q_Q(SingleApplication);
// Start a QLocalServer to listen for connections
server = new QLocalServer();
QLocalServer::removeServer(serverName);
server->listen(serverName);
QObject::connect(server, SIGNAL(newConnection()), q, SLOT(slotConnectionEstablished()));
}
#ifdef Q_OS_UNIX
void crashHandler()
{
// This guarantees the program will work even with multiple
// instances of SingleApplication in different threads.
// Which in my opinion is idiotic, but lets handle that too.
{
sharedMemMutex.lock();
sharedMem.append(memory);
sharedMemMutex.unlock();
}
// Handle any further termination signals to ensure the
// QSharedMemory block is deleted even if the process crashes
signal(SIGSEGV, SingleApplicationPrivate::terminate);
signal(SIGABRT, SingleApplicationPrivate::terminate);
signal(SIGFPE, SingleApplicationPrivate::terminate);
signal(SIGILL, SingleApplicationPrivate::terminate);
signal(SIGINT, SingleApplicationPrivate::terminate);
signal(SIGTERM, SingleApplicationPrivate::terminate);
}
static void terminate(int signum)
{
while( ! sharedMem.empty() ) {
delete sharedMem.back();
sharedMem.pop_back();
}
::exit(128 + signum);
}
static QList<QSharedMemory*> sharedMem;
static QMutex sharedMemMutex;
#endif
QSharedMemory *memory;
SingleApplication *q_ptr;
QLocalServer *server;
QLocalSocket *socket;
};
#ifdef Q_OS_UNIX
QList<QSharedMemory*> SingleApplicationPrivate::sharedMem;
QMutex SingleApplicationPrivate::sharedMemMutex;
#endif
/**
* @brief Constructor. Checks and fires up LocalServer or closes the program
* if another instance already exists
* @param argc
* @param argv
*/
SingleApplication::SingleApplication(int &argc, char *argv[])
: app_t(argc, argv), d_ptr(new SingleApplicationPrivate(this))
{
Q_D(SingleApplication);
QString serverName = app_t::organizationName() + app_t::applicationName();
serverName.replace(QRegExp("[^\\w\\-. ]"), "");
// Guarantee thread safe behaviour with a shared memory block
d->memory = new QSharedMemory(serverName);
// Create a shared memory block with a minimum size of 1 byte
if( d->memory->create(1, QSharedMemory::ReadOnly) )
{
#ifdef Q_OS_UNIX
// Handle any further termination signals to ensure the
// QSharedMemory block is deleted even if the process crashes
d->crashHandler();
#endif
// Successful creation means that no main process exists
// So we start a Local Server to listen for connections
d->startServer(serverName);
} else {
// Connect to the Local Server of the main process to notify it
// that a new process had been started
d->socket = new QLocalSocket();
d->socket->connectToServer(serverName);
// Even though a shared memory block exists, the original application
// might have crashed.
// So only after a successful connection is the second instance
// terminated.
if( d->socket->waitForConnected(100) )
{
// Terminate the program using STDLib's exit function
::exit(EXIT_SUCCESS);
} else {
delete d->memory;
::exit(EXIT_SUCCESS);
}
}
}
/**
* @brief Destructor
*/
SingleApplication::~SingleApplication()
{
Q_D(SingleApplication);
delete d->memory;
d->server->close();
}
/**
* @brief Executed when the showUp command is sent to LocalServer
*/
void SingleApplication::slotConnectionEstablished()
{
Q_D(SingleApplication);
QLocalSocket *socket = d->server->nextPendingConnection();
socket->close();
delete socket;
Q_EMIT showUp();
}
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