From 46b2204a3fee86b61568946896c866894a77bec9 Mon Sep 17 00:00:00 2001 From: Itay Grudev Date: Fri, 27 Jul 2018 04:29:55 +0300 Subject: Proposed SA changes still containing a race condition (#48) --- singleapplication.cpp | 429 +++++++------------------------------------------- 1 file changed, 59 insertions(+), 370 deletions(-) (limited to 'singleapplication.cpp') diff --git a/singleapplication.cpp b/singleapplication.cpp index a333a62..8dd94a8 100644 --- a/singleapplication.cpp +++ b/singleapplication.cpp @@ -1,6 +1,6 @@ // The MIT License (MIT) // -// Copyright (c) Itay Grudev 2015 - 2016 +// Copyright (c) Itay Grudev 2015 - 2018 // // Permission is hereby granted, free of charge, to any person obtaining a copy // of this software and associated documentation files (the "Software"), to deal @@ -20,355 +20,15 @@ // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN // THE SOFTWARE. -#include - -#include -#include +#include +#include +#include #include -#include #include -#include -#include -#include -#include -#include - -#ifdef Q_OS_UNIX - #include - #include -#endif - -#ifdef Q_OS_WIN - #include - #include -#endif #include "singleapplication.h" #include "singleapplication_p.h" - -SingleApplicationPrivate::SingleApplicationPrivate( SingleApplication *q_ptr ) : q_ptr( q_ptr ) { - server = nullptr; - socket = nullptr; -} - -SingleApplicationPrivate::~SingleApplicationPrivate() -{ - if( socket != nullptr ) { - socket->close(); - delete socket; - } - - memory->lock(); - InstancesInfo* inst = static_cast(memory->data()); - if( server != nullptr ) { - server->close(); - delete server; - inst->primary = false; - inst->primaryPid = -1; - } - memory->unlock(); - - delete memory; -} - -void SingleApplicationPrivate::genBlockServerName( int timeout ) -{ - QCryptographicHash appData( QCryptographicHash::Sha256 ); - appData.addData( "SingleApplication", 17 ); - appData.addData( SingleApplication::app_t::applicationName().toUtf8() ); - appData.addData( SingleApplication::app_t::organizationName().toUtf8() ); - appData.addData( SingleApplication::app_t::organizationDomain().toUtf8() ); - - if( ! (options & SingleApplication::Mode::ExcludeAppVersion) ) { - appData.addData( SingleApplication::app_t::applicationVersion().toUtf8() ); - } - - if( ! (options & SingleApplication::Mode::ExcludeAppPath) ) { -#ifdef Q_OS_WIN - appData.addData( SingleApplication::app_t::applicationFilePath().toLower().toUtf8() ); -#else - appData.addData( SingleApplication::app_t::applicationFilePath().toUtf8() ); -#endif - } - - // User level block requires a user specific data in the hash - if( options & SingleApplication::Mode::User ) { -#ifdef Q_OS_WIN - Q_UNUSED(timeout); - wchar_t username [ UNLEN + 1 ]; - // Specifies size of the buffer on input - DWORD usernameLength = UNLEN + 1; - if( GetUserNameW( username, &usernameLength ) ) { - appData.addData( QString::fromWCharArray(username).toUtf8() ); - } else { - appData.addData( QStandardPaths::standardLocations( QStandardPaths::HomeLocation ).join("").toUtf8() ); - } -#endif -#ifdef Q_OS_UNIX - QProcess process; - process.start( "whoami" ); - if( process.waitForFinished( timeout ) && - process.exitCode() == QProcess::NormalExit) { - appData.addData( process.readLine() ); - } else { - appData.addData( - QDir( - QStandardPaths::standardLocations( QStandardPaths::HomeLocation ).first() - ).absolutePath().toUtf8() - ); - } -#endif - } - - // Replace the backslash in RFC 2045 Base64 [a-zA-Z0-9+/=] to comply with - // server naming requirements. - blockServerName = appData.result().toBase64().replace("/", "_"); -} - -void SingleApplicationPrivate::startPrimary( bool resetMemory ) -{ - Q_Q(SingleApplication); - -#ifdef Q_OS_UNIX - // Handle any further termination signals to ensure the - // QSharedMemory block is deleted even if the process crashes - crashHandler(); -#endif - // Successful creation means that no main process exists - // So we start a QLocalServer to listen for connections - QLocalServer::removeServer( blockServerName ); - server = new QLocalServer(); - - // Restrict access to the socket according to the - // SingleApplication::Mode::User flag on User level or no restrictions - if( options & SingleApplication::Mode::User ) { - server->setSocketOptions( QLocalServer::UserAccessOption ); - } else { - server->setSocketOptions( QLocalServer::WorldAccessOption ); - } - - server->listen( blockServerName ); - QObject::connect( - server, - &QLocalServer::newConnection, - this, - &SingleApplicationPrivate::slotConnectionEstablished - ); - - // Reset the number of connections - memory->lock(); - InstancesInfo* inst = static_cast(memory->data()); - - if( resetMemory ) { - inst->secondary = 0; - } - - inst->primary = true; - inst->primaryPid = q->applicationPid(); - - memory->unlock(); - - instanceNumber = 0; -} - -void SingleApplicationPrivate::startSecondary() -{ -#ifdef Q_OS_UNIX - // Handle any further termination signals to ensure the - // QSharedMemory block is deleted even if the process crashes - crashHandler(); -#endif -} - -void SingleApplicationPrivate::connectToPrimary( int msecs, ConnectionType connectionType ) -{ - // Connect to the Local Server of the Primary Instance if not already - // connected. - if( socket == nullptr ) { - socket = new QLocalSocket(); - } - - // If already connected - we are done; - if( socket->state() == QLocalSocket::ConnectedState ) - return; - - // If not connect - if( socket->state() == QLocalSocket::UnconnectedState || - socket->state() == QLocalSocket::ClosingState ) { - socket->connectToServer( blockServerName ); - } - - // Wait for being connected - if( socket->state() == QLocalSocket::ConnectingState ) { - socket->waitForConnected( msecs ); - } - - // Initialisation message according to the SingleApplication protocol - if( socket->state() == QLocalSocket::ConnectedState ) { - // Notify the parent that a new instance had been started; - QByteArray initMsg; - QDataStream writeStream(&initMsg, QIODevice::WriteOnly); - writeStream.setVersion(QDataStream::Qt_5_6); - writeStream << blockServerName.toLatin1(); - writeStream << static_cast(connectionType); - writeStream << instanceNumber; - quint16 checksum = qChecksum(initMsg.constData(), static_cast(initMsg.length())); - writeStream << checksum; - - // The header indicates the message length that follows - QByteArray header; - QDataStream headerStream(&header, QIODevice::WriteOnly); - headerStream.setVersion(QDataStream::Qt_5_6); - headerStream << (quint64) initMsg.length(); - - socket->write( header ); - socket->write( initMsg ); - socket->flush(); - socket->waitForBytesWritten( msecs ); - } -} - -qint64 SingleApplicationPrivate::primaryPid() -{ - qint64 pid; - - memory->lock(); - InstancesInfo* inst = static_cast(memory->data()); - pid = inst->primaryPid; - memory->unlock(); - - return pid; -} - -#ifdef Q_OS_UNIX - void SingleApplicationPrivate::crashHandler() - { - // Handle any further termination signals to ensure the - // QSharedMemory block is deleted even if the process crashes - signal( SIGHUP, SingleApplicationPrivate::terminate ); // 1 - signal( SIGINT, SingleApplicationPrivate::terminate ); // 2 - signal( SIGQUIT, SingleApplicationPrivate::terminate ); // 3 - signal( SIGILL, SingleApplicationPrivate::terminate ); // 4 - signal( SIGABRT, SingleApplicationPrivate::terminate ); // 6 - signal( SIGFPE, SingleApplicationPrivate::terminate ); // 8 - signal( SIGBUS, SingleApplicationPrivate::terminate ); // 10 - signal( SIGSEGV, SingleApplicationPrivate::terminate ); // 11 - signal( SIGSYS, SingleApplicationPrivate::terminate ); // 12 - signal( SIGPIPE, SingleApplicationPrivate::terminate ); // 13 - signal( SIGALRM, SingleApplicationPrivate::terminate ); // 14 - signal( SIGTERM, SingleApplicationPrivate::terminate ); // 15 - signal( SIGXCPU, SingleApplicationPrivate::terminate ); // 24 - signal( SIGXFSZ, SingleApplicationPrivate::terminate ); // 25 - } - - void SingleApplicationPrivate::terminate( int signum ) - { - delete ((SingleApplication*)QCoreApplication::instance())->d_ptr; - ::exit( 128 + signum ); - } -#endif - -/** - * @brief Executed when a connection has been made to the LocalServer - */ -void SingleApplicationPrivate::slotConnectionEstablished() -{ - Q_Q(SingleApplication); - - QLocalSocket *nextConnSocket = server->nextPendingConnection(); - - quint32 instanceId = 0; - ConnectionType connectionType = InvalidConnection; - if( nextConnSocket->waitForReadyRead( 100 ) ) { - // read the fields in same order and format as written - QDataStream headerStream(nextConnSocket); - headerStream.setVersion(QDataStream::Qt_5_6); - - // Read the header to know the message length - quint64 msgLen = 0; - headerStream >> msgLen; - - if (msgLen >= sizeof(quint16)) { - // Read the message body - QByteArray msgBytes = nextConnSocket->read(msgLen); - QDataStream readStream(msgBytes); - readStream.setVersion(QDataStream::Qt_5_6); - - // server name - QByteArray latin1Name; - readStream >> latin1Name; - - // connection type - quint8 connType = InvalidConnection; - readStream >> connType; - connectionType = static_cast(connType); - - // instance id - readStream >> instanceId; - - // checksum - quint16 msgChecksum = 0; - readStream >> msgChecksum; - - const quint16 actualChecksum = qChecksum(msgBytes.constData(), static_cast(msgBytes.length() - sizeof(quint16))); - - if (readStream.status() != QDataStream::Ok || QLatin1String(latin1Name) != blockServerName || msgChecksum != actualChecksum) { - connectionType = InvalidConnection; - } - } - } - - if( connectionType == InvalidConnection ) { - nextConnSocket->close(); - delete nextConnSocket; - return; - } - - QObject::connect( - nextConnSocket, - &QLocalSocket::aboutToClose, - this, - [nextConnSocket, instanceId, this]() { - Q_EMIT this->slotClientConnectionClosed( nextConnSocket, instanceId ); - } - ); - - QObject::connect( - nextConnSocket, - &QLocalSocket::readyRead, - this, - [nextConnSocket, instanceId, this]() { - Q_EMIT this->slotDataAvailable( nextConnSocket, instanceId ); - } - ); - - if( connectionType == NewInstance || ( - connectionType == SecondaryInstance && - options & SingleApplication::Mode::SecondaryNotification - ) - ) { - Q_EMIT q->instanceStarted(); - } - - if( nextConnSocket->bytesAvailable() > 0 ) { - Q_EMIT this->slotDataAvailable( nextConnSocket, instanceId ); - } -} - -void SingleApplicationPrivate::slotDataAvailable( QLocalSocket *dataSocket, quint32 instanceId ) -{ - Q_Q(SingleApplication); - Q_EMIT q->receivedMessage( instanceId, dataSocket->readAll() ); -} - -void SingleApplicationPrivate::slotClientConnectionClosed( QLocalSocket *closedSocket, quint32 instanceId ) -{ - if( closedSocket->bytesAvailable() > 0 ) - Q_EMIT slotDataAvailable( closedSocket, instanceId ); - closedSocket->deleteLater(); -} - /** * @brief Constructor. Checks and fires up LocalServer or closes the program * if another instance already exists @@ -386,52 +46,81 @@ SingleApplication::SingleApplication( int &argc, char *argv[], bool allowSeconda // Generating an application ID used for identifying the shared memory // block and QLocalServer - d->genBlockServerName( timeout ); + d->genBlockServerName(); - // Guarantee thread safe behaviour with a shared memory block. Also by - // explicitly attaching it and then deleting it we make sure that the - // memory is deleted even if the process had crashed on Unix. #ifdef Q_OS_UNIX + // By explicitly attaching it and then deleting it we make sure that the + // memory is deleted even after the process has crashed on Unix. d->memory = new QSharedMemory( d->blockServerName ); d->memory->attach(); delete d->memory; #endif + // Guarantee thread safe behaviour with a shared memory block. d->memory = new QSharedMemory( d->blockServerName ); // Create a shared memory block if( d->memory->create( sizeof( InstancesInfo ) ) ) { - d->startPrimary( true ); - return; + // Initialize the shared memory block + d->memory->lock(); + d->initializeMemoryBlock(); + d->memory->unlock(); } else { // Attempt to attach to the memory segment - if( d->memory->attach() ) { - d->memory->lock(); - InstancesInfo* inst = static_cast(d->memory->data()); + if( ! d->memory->attach() ) { + qCritical() << "SingleApplication: Unable to attach to shared memory block."; + qCritical() << d->memory->errorString(); + delete d; + ::exit( EXIT_FAILURE ); + } + } + + InstancesInfo* inst = static_cast( d->memory->data() ); + QTime time; + time.start(); + + // Make sure the shared memory block is initialised and in consistent state + while( true ) { + d->memory->lock(); + + if( d->blockChecksum() == inst->checksum ) break; + + if( time.elapsed() > 5000 ) { + qWarning() << "SingleApplication: Shared memory block has been in an inconsistent state from more than 5s. Assuming primary instance failure."; + d->initializeMemoryBlock(); + } - if( ! inst->primary ) { - d->startPrimary( false ); - d->memory->unlock(); - return; - } + d->memory->unlock(); - // Check if another instance can be started - if( allowSecondary ) { - inst->secondary += 1; - d->instanceNumber = inst->secondary; - d->startSecondary(); - if( d->options & Mode::SecondaryNotification ) { - d->connectToPrimary( timeout, SingleApplicationPrivate::SecondaryInstance ); - } - d->memory->unlock(); - return; - } + // Random sleep here limits the probability of a colision between two racing apps + qsrand( QDateTime::currentMSecsSinceEpoch() % std::numeric_limits::max() ); + QThread::sleep( 8 + static_cast ( static_cast ( qrand() ) / RAND_MAX * 10 ) ); + } + + if( inst->primary == false) { + d->startPrimary(); + d->memory->unlock(); + return; + } - d->memory->unlock(); + // Check if another instance can be started + if( allowSecondary ) { + inst->secondary += 1; + inst->checksum = d->blockChecksum(); + d->instanceNumber = inst->secondary; + d->startSecondary(); + if( d->options & Mode::SecondaryNotification ) { + d->connectToPrimary( timeout, SingleApplicationPrivate::SecondaryInstance ); } + d->memory->unlock(); + return; } + d->memory->unlock(); + d->connectToPrimary( timeout, SingleApplicationPrivate::NewInstance ); + delete d; + ::exit( EXIT_SUCCESS ); } -- cgit v1.2.1