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#include "LocalPeer.h"
#include <QCoreApplication>
#include <QDataStream>
#include <QTime>
#include <QLocalServer>
#include <QLocalSocket>
#include <QDir>
#include "LockedFile.h"

#if defined(Q_OS_WIN)
#include <QLibrary>
#include <qt_windows.h>
typedef BOOL(WINAPI*PProcessIdToSessionId)(DWORD,DWORD*);
static PProcessIdToSessionId pProcessIdToSessionId = 0;
#endif
#if defined(Q_OS_UNIX)
#include <sys/types.h>
#include <unistd.h>
#endif

#include <chrono>
#include <thread>
#include <QCryptographicHash>

static const char* ack = "ack";

ApplicationId ApplicationId::fromTraditionalApp()
{
	QString protoId = QCoreApplication::applicationFilePath();
#if defined(Q_OS_WIN)
	protoId = protoId.toLower();
#endif
	auto prefix = protoId.section(QLatin1Char('/'), -1);
	prefix.remove(QRegExp("[^a-zA-Z]"));
	prefix.truncate(6);
	QByteArray idc = protoId.toUtf8();
	quint16 idNum = qChecksum(idc.constData(), idc.size());
	auto socketName = QLatin1String("qtsingleapp-") + prefix + QLatin1Char('-') + QString::number(idNum, 16);
#if defined(Q_OS_WIN)
	if (!pProcessIdToSessionId)
	{
		QLibrary lib("kernel32");
		pProcessIdToSessionId = (PProcessIdToSessionId)lib.resolve("ProcessIdToSessionId");
	}
	if (pProcessIdToSessionId)
	{
		DWORD sessionId = 0;
		pProcessIdToSessionId(GetCurrentProcessId(), &sessionId);
		socketName += QLatin1Char('-') + QString::number(sessionId, 16);
	}
#else
	socketName += QLatin1Char('-') + QString::number(::getuid(), 16);
#endif
	return ApplicationId(socketName);
}

ApplicationId ApplicationId::fromPathAndVersion(const QString& dataPath, const QString& version)
{
	QCryptographicHash shasum(QCryptographicHash::Algorithm::Sha1);
	QString result = dataPath + QLatin1Char('-') + version;
	shasum.addData(result.toUtf8());
	return ApplicationId(QLatin1String("qtsingleapp-") + QString::fromLatin1(shasum.result().toHex()));
}

ApplicationId ApplicationId::fromCustomId(const QString& id)
{
	return ApplicationId(QLatin1String("qtsingleapp-") + id);
}

LocalPeer::LocalPeer(QObject * parent, const ApplicationId &appId)
	: QObject(parent), id(appId)
{
	socketName = id.toString();
	server.reset(new QLocalServer());
	QString lockName = QDir(QDir::tempPath()).absolutePath() + QLatin1Char('/') + socketName + QLatin1String("-lockfile");
	lockFile.reset(new LockedFile(lockName));
	lockFile->open(QIODevice::ReadWrite);
}

LocalPeer::~LocalPeer()
{
}

ApplicationId LocalPeer::applicationId() const
{
	return id;
}

bool LocalPeer::isClient()
{
	if (lockFile->isLocked())
		return false;

	if (!lockFile->lock(LockedFile::WriteLock, false))
		return true;

	bool res = server->listen(socketName);
#if defined(Q_OS_UNIX)
	// ### Workaround
	if (!res && server->serverError() == QAbstractSocket::AddressInUseError) {
		QFile::remove(QDir::cleanPath(QDir::tempPath())+QLatin1Char('/')+socketName);
		res = server->listen(socketName);
	}
#endif
	if (!res)
		qWarning("QtSingleCoreApplication: listen on local socket failed, %s", qPrintable(server->errorString()));
	QObject::connect(server.get(), SIGNAL(newConnection()), SLOT(receiveConnection()));
	return false;
}


bool LocalPeer::sendMessage(const QString &message, int timeout)
{
	if (!isClient())
		return false;

	QLocalSocket socket;
	bool connOk = false;
	for(int i = 0; i < 2; i++) {
		// Try twice, in case the other instance is just starting up
		socket.connectToServer(socketName);
		connOk = socket.waitForConnected(timeout/2);
		if (connOk || i)
		{
			break;
		}
		std::this_thread::sleep_for(std::chrono::milliseconds(250));
	}
	if (!connOk)
	{
		return false;
	}

	QByteArray uMsg(message.toUtf8());
	QDataStream ds(&socket);

	ds.writeBytes(uMsg.constData(), uMsg.size());
	if(!socket.waitForBytesWritten(timeout))
	{
		return false;
	}

	// wait for 'ack'
	if(!socket.waitForReadyRead(timeout))
	{
		return false;
	}

	// make sure we got 'ack'
	if(!(socket.read(qstrlen(ack)) == ack))
	{
		return false;
	}
	return true;
}


void LocalPeer::receiveConnection()
{
	QLocalSocket* socket = server->nextPendingConnection();
	if (!socket)
	{
		return;
	}

	while (socket->bytesAvailable() < (int)sizeof(quint32))
	{
		socket->waitForReadyRead();
	}
	QDataStream ds(socket);
	QByteArray uMsg;
	quint32 remaining;
	ds >> remaining;
	uMsg.resize(remaining);
	int got = 0;
	char* uMsgBuf = uMsg.data();
	do
	{
		got = ds.readRawData(uMsgBuf, remaining);
		remaining -= got;
		uMsgBuf += got;
	} while (remaining && got >= 0 && socket->waitForReadyRead(2000));
	if (got < 0)
	{
		qWarning("QtLocalPeer: Message reception failed %s", socket->errorString().toLatin1().constData());
		delete socket;
		return;
	}
	QString message(QString::fromUtf8(uMsg));
	socket->write(ack, qstrlen(ack));
	socket->waitForBytesWritten(1000);
	socket->waitForDisconnected(1000); // make sure client reads ack
	delete socket;
	emit messageReceived(message); //### (might take a long time to return)
}