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#include "singleapplication.h"
#include <QSharedMemory>
#include <QLocalSocket>
#include <QLocalServer>
#include <QMutex>
#include <cstdlib>
#ifdef Q_OS_UNIX
#include <signal.h>
#include <unistd.h>
#endif
class SingleApplicationPrivate {
public:
SingleApplicationPrivate(SingleApplication *q_ptr) : q_ptr(q_ptr) { }
void startServer(QString &serverName)
{
// Start a QLocalServer to listen for connections
server = new QLocalServer();
server->removeServer(serverName);
server->listen(serverName);
QObject::connect(server, SIGNAL(newConnection()), q_ptr, 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[])
: QAPPLICATION_CLASS(argc, argv), d_ptr(new SingleApplicationPrivate(this))
{
QString serverName = QAPPLICATION_CLASS::organizationName() + QAPPLICATION_CLASS::applicationName();
serverName.replace(QRegExp("[^\\w\\-. ]"), "");
// Garantee thread safe behaviour with a shared memory block
d_ptr->memory = new QSharedMemory(serverName);
// Create a shared memory block with a minimum size of 1 byte
if( d_ptr->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_ptr->crashHandler();
#endif
// Successful creation means that no main process exists
// So we start a Local Server to listen for connections
d_ptr->startServer(serverName);
} else {
// Connect to the Local Server of the main process to notify it
// that a new process had been started
d_ptr->socket = new QLocalSocket();
d_ptr->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_ptr->socket->waitForConnected(100) )
{
::exit(EXIT_SUCCESS); // Terminate the program using STDLib's exit function
} else {
delete d_ptr->memory;
::exit(EXIT_SUCCESS);
}
}
}
/**
* @brief Destructor
*/
SingleApplication::~SingleApplication()
{
delete d_ptr->memory;
d_ptr->server->close();
}
/**
* @brief Executed when the showUp command is sent to LocalServer
*/
void SingleApplication::slotConnectionEstablished()
{
QLocalSocket *socket = d_ptr->server->nextPendingConnection();
socket->close();
delete socket;
emit showUp();
}
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