Session.cpp

/*
    SPDX-FileCopyrightText: 2006-2008 Robert Knight <robertknight@gmail.com>
    SPDX-FileCopyrightText: 1997, 1998 Lars Doelle <lars.doelle@on-line.de>
    SPDX-FileCopyrightText: 2009 Thomas Dreibholz <dreibh@iem.uni-due.de>

    SPDX-License-Identifier: GPL-2.0-or-later
*/

// Own
#include "Session.h"

// Standard
#include <csignal>
#include <cstdlib>
#include <unistd.h>

// Qt
#include <QApplication>
#include <QColor>
#include <QDir>
#include <QFile>
#include <QKeyEvent>

// KDE
#include <KConfigGroup>
#include <KIO/DesktopExecParser>
#include <KLocalizedString>
#include <KNotification>
#include <KProcess>
#include <KShell>
#include <kcoreaddons_version.h>

// Konsole
#include <sessionadaptor.h>

#include "Pty.h"
#include "SSHProcessInfo.h"
#include "SessionManager.h"
#include "ShellCommand.h"
#include "Vt102Emulation.h"
#include "ZModemDialog.h"
#include "history/HistoryTypeFile.h"
#include "history/HistoryTypeNone.h"
#include "history/compact/CompactHistoryType.h"
#include "konsoledebug.h"
#include "profile/Profile.h"
#include "profile/ProfileManager.h"

#include "terminalDisplay/TerminalDisplay.h"
#include "terminalDisplay/TerminalScrollBar.h"

// Linux
#ifdef HAVE_GETPWUID
#include <pwd.h>
#include <sys/types.h>
#endif

using namespace Konsole;

int Session::lastSessionId = 0;
static bool show_disallow_certain_dbus_methods_message = true;

static const int ZMODEM_BUFFER_SIZE = 1048576; // 1 Mb

Session::Session(QObject *parent)
    : QObject(parent)
    , _uniqueIdentifier(QUuid())
    , _shellProcess(nullptr)
    , _emulation(nullptr)
    , _views(QList<TerminalDisplay *>())
    , _monitorActivity(false)
    , _monitorSilence(false)
    , _notifiedActivity(false)
    , _silenceSeconds(10)
    , _silenceTimer(nullptr)
    , _activityTimer(nullptr)
    , _autoClose(true)
    , _closePerUserRequest(false)
    , _nameTitle(QString())
    , _displayTitle(QString())
    , _userTitle(QString())
    , _localTabTitleFormat(QString())
    , _remoteTabTitleFormat(QString())
    , _tabTitleSetByUser(false)
    , _tabColorSetByUser(false)
    , _iconName(QString())
    , _iconText(QString())
    , _addToUtmp(true)
    , _flowControlEnabled(true)
    , _program(QString())
    , _arguments(QStringList())
    , _environment(QStringList())
    , _sessionId(0)
    , _initialWorkingDir(QString())
    , _currentWorkingDir(QString())
    , _reportedWorkingUrl(QUrl())
    , _sessionProcessInfo(nullptr)
    , _foregroundProcessInfo(nullptr)
    , _foregroundPid(0)
    , _zmodemBusy(false)
    , _zmodemProc(nullptr)
    , _zmodemProgress(nullptr)
    , _hasDarkBackground(false)
    , _preferredSize(QSize())
    , _readOnly(false)
    , _isPrimaryScreen(true)
{
    _uniqueIdentifier = QUuid::createUuid();

    // prepare DBus communication
    new SessionAdaptor(this);
    _sessionId = ++lastSessionId;
    QDBusConnection::sessionBus().registerObject(QLatin1String("/Sessions/") + QString::number(_sessionId), this);

    // create emulation backend
    _emulation = new Vt102Emulation();
    _emulation->reset();

    connect(_emulation, &Konsole::Emulation::sessionAttributeChanged, this, &Konsole::Session::setSessionAttribute);
    connect(_emulation, &Konsole::Emulation::bell, this, [this]() {
        Q_EMIT bellRequest(i18n("Bell in '%1' (Session '%2')", _displayTitle, _nameTitle));
        this->setPendingNotification(Notification::Bell);
    });
    connect(_emulation, &Konsole::Emulation::zmodemDownloadDetected, this, &Konsole::Session::fireZModemDownloadDetected);
    connect(_emulation, &Konsole::Emulation::zmodemUploadDetected, this, &Konsole::Session::fireZModemUploadDetected);
    connect(_emulation, &Konsole::Emulation::profileChangeCommandReceived, this, &Konsole::Session::profileChangeCommandReceived);
    connect(_emulation, &Konsole::Emulation::flowControlKeyPressed, this, &Konsole::Session::updateFlowControlState);
    connect(_emulation, &Konsole::Emulation::primaryScreenInUse, this, &Konsole::Session::onPrimaryScreenInUse);
    connect(_emulation, &Konsole::Emulation::selectionChanged, this, &Konsole::Session::selectionChanged);
    connect(_emulation, &Konsole::Emulation::imageResizeRequest, this, &Konsole::Session::resizeRequest);
    connect(_emulation, &Konsole::Emulation::sessionAttributeRequest, this, &Konsole::Session::sessionAttributeRequest);

    // create new teletype for I/O with shell process
    openTeletype(-1, true);

    // setup timer for monitoring session activity & silence
    _silenceTimer = new QTimer(this);
    _silenceTimer->setSingleShot(true);
    connect(_silenceTimer, &QTimer::timeout, this, &Konsole::Session::silenceTimerDone);

    _activityTimer = new QTimer(this);
    _activityTimer->setSingleShot(true);
    connect(_activityTimer, &QTimer::timeout, this, &Konsole::Session::activityTimerDone);
}

Session::~Session()
{
    delete _foregroundProcessInfo;
    delete _sessionProcessInfo;
    delete _emulation;
    delete _shellProcess;
    delete _zmodemProc;
}

void Session::openTeletype(int fd, bool runShell)
{
    if (isRunning()) {
        qWarning() << "Attempted to open teletype in a running session.";
        return;
    }

    delete _shellProcess;

    if (fd < 0) {
        _shellProcess = new Pty();
    } else {
        _shellProcess = new Pty(fd);
    }

    _shellProcess->setUtf8Mode(_emulation->utf8());

    // connect the I/O between emulator and pty process
    connect(_shellProcess, &Konsole::Pty::receivedData, this, &Konsole::Session::onReceiveBlock);
    connect(_emulation, &Konsole::Emulation::sendData, _shellProcess, &Konsole::Pty::sendData);

    // UTF8 mode
    connect(_emulation, &Konsole::Emulation::useUtf8Request, _shellProcess, &Konsole::Pty::setUtf8Mode);

    // get notified when the pty process is finished
    connect(_shellProcess, QOverload<int, QProcess::ExitStatus>::of(&Konsole::Pty::finished), this, &Konsole::Session::done);

    // emulator size
    connect(_emulation, &Konsole::Emulation::imageSizeChanged, this, &Konsole::Session::updateWindowSize);
    if (fd < 0 || runShell) {
        // Using a queued connection guarantees that starting the session
        // is delayed until all (both) image size updates at startup have
        // been processed. See #203185 and #412598.
        connect(_emulation, &Konsole::Emulation::imageSizeInitialized, this, &Konsole::Session::run, Qt::QueuedConnection);
    } else {
        // run needs to be disconnected, as it may be already connected by the constructor
        disconnect(_emulation, &Konsole::Emulation::imageSizeInitialized, this, &Konsole::Session::run);
    }
}

WId Session::windowId() const
{
    // Returns a window ID for this session which is used
    // to set the WINDOWID environment variable in the shell
    // process.
    //
    // Sessions can have multiple views or no views, which means
    // that a single ID is not always going to be accurate.
    //
    // If there are no views, the window ID is just 0.  If
    // there are multiple views, then the window ID for the
    // top-level window which contains the first view is
    // returned

    if (_views.count() == 0) {
        return 0;
    } else {
        /**
         * compute the windows id to use
         * doesn't call winId on some widget, as this might lead
         * to rendering artifacts as this will trigger the
         * creation of a native window, see https://doc.qt.io/qt-5/qwidget.html#winId
         * instead, use https://doc.qt.io/qt-5/qwidget.html#effectiveWinId
         */
        QWidget *widget = _views.first();
        Q_ASSERT(widget);
        return widget->effectiveWinId();
    }
}

void Session::setDarkBackground(bool darkBackground)
{
    _hasDarkBackground = darkBackground;
}

bool Session::isRunning() const
{
    return (_shellProcess != nullptr) && (_shellProcess->state() == QProcess::Running);
}

bool Session::hasFocus() const
{
    return std::any_of(_views.constBegin(), _views.constEnd(), [](const TerminalDisplay *display) {
        return display->hasFocus();
    });
}

void Session::setCodec(QTextCodec *codec)
{
    if (isReadOnly()) {
        return;
    }

    emulation()->setCodec(codec);

    Q_EMIT sessionCodecChanged(codec);
}

bool Session::setCodec(const QByteArray &name)
{
    QTextCodec *codec = QTextCodec::codecForName(name);

    if (codec != nullptr) {
        setCodec(codec);
        return true;
    } else {
        return false;
    }
}

QByteArray Session::codec()
{
    return _emulation->codec()->name();
}

void Session::setProgram(const QString &program)
{
    _program = ShellCommand::expand(program);
}

void Session::setArguments(const QStringList &arguments)
{
    _arguments = ShellCommand::expand(arguments);
}

void Session::setInitialWorkingDirectory(const QString &dir)
{
    _initialWorkingDir = validDirectory(KShell::tildeExpand(ShellCommand::expand(dir)));
}

QString Session::currentWorkingDirectory()
{
    if (_reportedWorkingUrl.isValid() && _reportedWorkingUrl.isLocalFile()) {
        return _reportedWorkingUrl.path();
    }

    // only returned cached value
    if (_currentWorkingDir.isEmpty()) {
        updateWorkingDirectory();
    }

    return _currentWorkingDir;
}
void Session::updateWorkingDirectory()
{
    updateSessionProcessInfo();

    const QString currentDir = _sessionProcessInfo->validCurrentDir();
    if (currentDir != _currentWorkingDir) {
        _currentWorkingDir = currentDir;
        Q_EMIT currentDirectoryChanged(_currentWorkingDir);
    }
}

QList<TerminalDisplay *> Session::views() const
{
    return _views;
}

void Session::addView(TerminalDisplay *widget)
{
    Q_ASSERT(!_views.contains(widget));

    _views.append(widget);

    // connect emulation - view signals and slots
    connect(widget, &Konsole::TerminalDisplay::keyPressedSignal, _emulation, &Konsole::Emulation::sendKeyEvent);
    connect(widget, &Konsole::TerminalDisplay::mouseSignal, _emulation, &Konsole::Emulation::sendMouseEvent);
    connect(widget, &Konsole::TerminalDisplay::sendStringToEmu, _emulation, &Konsole::Emulation::sendString);
    connect(widget, &Konsole::TerminalDisplay::peekPrimaryRequested, _emulation, &Konsole::Emulation::setPeekPrimary);

    // allow emulation to notify the view when the foreground process
    // indicates whether or not it is interested in Mouse Tracking events
    connect(_emulation, &Konsole::Emulation::programRequestsMouseTracking, widget, &Konsole::TerminalDisplay::setUsesMouseTracking);

    widget->setUsesMouseTracking(_emulation->programUsesMouseTracking());

    connect(_emulation, &Konsole::Emulation::enableAlternateScrolling, widget->scrollBar(), &Konsole::TerminalScrollBar::setAlternateScrolling);

    connect(_emulation, &Konsole::Emulation::programBracketedPasteModeChanged, widget, &Konsole::TerminalDisplay::setBracketedPasteMode);

    widget->setBracketedPasteMode(_emulation->programBracketedPasteMode());

    widget->setScreenWindow(_emulation->createWindow());

    _emulation->setCurrentTerminalDisplay(widget);

    // connect view signals and slots
    connect(widget, &Konsole::TerminalDisplay::changedContentSizeSignal, this, &Konsole::Session::onViewSizeChange);

    connect(widget, &Konsole::TerminalDisplay::destroyed, this, &Konsole::Session::viewDestroyed);

    connect(widget, &Konsole::TerminalDisplay::compositeFocusChanged, _emulation, &Konsole::Emulation::focusChanged);

    connect(_emulation, &Konsole::Emulation::setCursorStyleRequest, widget, &Konsole::TerminalDisplay::setCursorStyle);
    connect(_emulation, &Konsole::Emulation::resetCursorStyleRequest, widget, &Konsole::TerminalDisplay::resetCursorStyle);

    connect(widget, &Konsole::TerminalDisplay::keyPressedSignal, this, &Konsole::Session::resetNotifications);
}

void Session::viewDestroyed(QObject *view)
{
    auto *display = reinterpret_cast<TerminalDisplay *>(view);

    Q_ASSERT(_views.contains(display));

    removeView(display);
}

void Session::removeView(TerminalDisplay *widget)
{
    _views.removeAll(widget);

    disconnect(widget, nullptr, this, nullptr);

    // disconnect
    //  - key presses signals from widget
    //  - mouse activity signals from widget
    //  - string sending signals from widget
    //
    //  ... and any other signals connected in addView()
    disconnect(widget, nullptr, _emulation, nullptr);

    // disconnect state change signals emitted by emulation
    disconnect(_emulation, nullptr, widget, nullptr);

    // close the session automatically when the last view is removed
    if (_views.count() == 0) {
        close();
    }
}

// Upon a KPty error, there is no description on what that error was...
// Check to see if the given program is executable.
QString Session::checkProgram(const QString &program)
{
    QString exec = program;

    if (exec.isEmpty()) {
        return QString();
    }

    QFileInfo info(exec);
    if (info.isAbsolute() && info.exists() && info.isExecutable()) {
        return exec;
    }

    exec = KIO::DesktopExecParser::executablePath(exec);
    exec = KShell::tildeExpand(exec);
    const QString pexec = QStandardPaths::findExecutable(exec);
    if (pexec.isEmpty()) {
        qCritical() << i18n("Could not find binary: ") << exec;
        return QString();
    }

    return exec;
}

void Session::terminalWarning(const QString &message)
{
    static const QByteArray warningText = i18nc("@info:shell Alert the user with red color text", "Warning: ").toLocal8Bit();
    QByteArray messageText = message.toLocal8Bit();

    static const char redPenOn[] = "\033[1m\033[31m";
    static const char redPenOff[] = "\033[0m";

    _emulation->receiveData(redPenOn, qstrlen(redPenOn));
    _emulation->receiveData("\n\r\n\r", 4);
    _emulation->receiveData(warningText.constData(), qstrlen(warningText.constData()));
    _emulation->receiveData(messageText.constData(), qstrlen(messageText.constData()));
    _emulation->receiveData("\n\r\n\r", 4);
    _emulation->receiveData(redPenOff, qstrlen(redPenOff));
}

QString Session::shellSessionId() const
{
    QString friendlyUuid(_uniqueIdentifier.toString());
    friendlyUuid.remove(QLatin1Char('-')).remove(QLatin1Char('{')).remove(QLatin1Char('}'));

    return friendlyUuid;
}

void Session::run()
{
    // FIXME: run() is called twice in some instances
    if (isRunning()) {
        qCDebug(KonsoleDebug) << "Attempted to re-run an already running session (" << processId() << ")";
        return;
    }

    // check that everything is in place to run the session
    if (_program.isEmpty()) {
        qWarning() << "Program to run not set.";
    }
    if (_arguments.isEmpty()) {
        qWarning() << "No command line arguments specified.";
    }
    if (_uniqueIdentifier.isNull()) {
        _uniqueIdentifier = QUuid::createUuid();
    }

    QStringList programs = {_program, QString::fromUtf8(qgetenv("SHELL")), QStringLiteral("/bin/sh")};

#ifdef HAVE_GETPWUID
    auto pw = getpwuid(getuid());
    // pw may be NULL
    if (pw != nullptr) {
        programs.insert(1, QString::fromLocal8Bit(pw->pw_shell));
    }
    // pw: Do not pass the returned pointer to free.
#endif

    QString exec;
    for (const auto &choice : programs) {
        exec = checkProgram(choice);
        if (!exec.isEmpty()) {
            break;
        }
    }

    // if nothing could be found (not even the fallbacks), print a warning and do not run
    if (exec.isEmpty()) {
        terminalWarning(i18n("Could not find an interactive shell to start."));
        return;
    }

    // if a program was specified via setProgram(), but it couldn't be found (but a fallback was), print a warning
    if (exec != checkProgram(_program)) {
        terminalWarning(i18n("Could not find '%1', starting '%2' instead.  Please check your profile settings.", _program, exec));
    } else if (exec != checkProgram(exec)) {
        terminalWarning(i18n("Could not find '%1', starting '%2' instead.  Please check your profile settings.", exec, checkProgram(exec)));
    }

    // if no arguments are specified, fall back to program name
    QStringList arguments = _arguments.join(QLatin1Char(' ')).isEmpty() ? QStringList() << exec : _arguments;

    if (!_initialWorkingDir.isEmpty()) {
        _shellProcess->setInitialWorkingDirectory(_initialWorkingDir);
    } else {
        _shellProcess->setInitialWorkingDirectory(QDir::currentPath());
    }

    _shellProcess->setFlowControlEnabled(_flowControlEnabled);
    _shellProcess->setEraseChar(_emulation->eraseChar());
    _shellProcess->setUseUtmp(_addToUtmp);

    // this is not strictly accurate use of the COLORFGBG variable.  This does not
    // tell the terminal exactly which colors are being used, but instead approximates
    // the color scheme as "black on white" or "white on black" depending on whether
    // the background color is deemed dark or not
    const QString backgroundColorHint = _hasDarkBackground ? QStringLiteral("COLORFGBG=15;0") : QStringLiteral("COLORFGBG=0;15");
    addEnvironmentEntry(backgroundColorHint);

    addEnvironmentEntry(QStringLiteral("SHELL_SESSION_ID=%1").arg(shellSessionId()));

    addEnvironmentEntry(QStringLiteral("WINDOWID=%1").arg(QString::number(windowId())));

    const QString dbusService = QDBusConnection::sessionBus().baseService();
    addEnvironmentEntry(QStringLiteral("KONSOLE_DBUS_SERVICE=%1").arg(dbusService));

    const QString dbusObject = QStringLiteral("/Sessions/%1").arg(QString::number(_sessionId));
    addEnvironmentEntry(QStringLiteral("KONSOLE_DBUS_SESSION=%1").arg(dbusObject));

    int result = _shellProcess->start(exec, arguments, _environment);
    if (result < 0) {
        terminalWarning(i18n("Could not start program '%1' with arguments '%2'.", exec, arguments.join(QLatin1String(" "))));
        terminalWarning(_shellProcess->errorString());
        return;
    }

    _shellProcess->setWriteable(false); // We are reachable via kwrited.

    Q_EMIT started();
}

void Session::setSessionAttribute(int what, const QString &caption)
{
    // set to true if anything has actually changed
    // eg. old _nameTitle != new _nameTitle
    bool modified = false;

    if ((what == IconNameAndWindowTitle) || (what == WindowTitle)) {
        if (_userTitle != caption) {
            _userTitle = caption;
            modified = true;
        }
    }

    if ((what == IconNameAndWindowTitle) || (what == IconName)) {
        if (_iconText != caption) {
            _iconText = caption;
            modified = true;
        }
    }

    if (what == TextColor || what == BackgroundColor) {
        QString colorString = caption.section(QLatin1Char(';'), 0, 0);
        QColor color = QColor(colorString);
        if (color.isValid()) {
            if (what == TextColor) {
                Q_EMIT changeForegroundColorRequest(color);
            } else {
                Q_EMIT changeBackgroundColorRequest(color);
            }
        }
    }

    if (what == SessionName) {
        if (_localTabTitleFormat != caption) {
            _localTabTitleFormat = caption;
            setTitle(Session::DisplayedTitleRole, caption);
            modified = true;
        }
    }

    /* The below use of 32 works but appears to non-standard.
       It is from a commit from 2004 c20973eca8776f9b4f15bee5fdcb5a3205aa69de
     */
    // change icon via \033]32;Icon\007
    if (what == SessionIcon) {
        if (_iconName != caption) {
            _iconName = caption;

            modified = true;
        }
    }

    if (what == CurrentDirectory) {
        _reportedWorkingUrl = QUrl::fromUserInput(caption);
        Q_EMIT currentDirectoryChanged(currentWorkingDirectory());
        modified = true;
    }

    if (what == ProfileChange) {
        Q_EMIT profileChangeCommandReceived(caption);
        return;
    }

    if (modified) {
        Q_EMIT sessionAttributeChanged();
    }
}

QString Session::userTitle() const
{
    return _userTitle;
}

void Session::setTabTitleFormat(TabTitleContext context, const QString &format)
{
    if (context == LocalTabTitle) {
        _localTabTitleFormat = format;
        ProcessInfo *process = getProcessInfo();
        process->setUserNameRequired(format.contains(QLatin1String("%u")));
    } else if (context == RemoteTabTitle) {
        _remoteTabTitleFormat = format;
    }
}

QString Session::tabTitleFormat(TabTitleContext context) const
{
    if (context == LocalTabTitle) {
        return _localTabTitleFormat;
    } else if (context == RemoteTabTitle) {
        return _remoteTabTitleFormat;
    }

    return QString();
}

void Session::tabTitleSetByUser(bool set)
{
    _tabTitleSetByUser = set;
}

bool Session::isTabTitleSetByUser() const
{
    return _tabTitleSetByUser;
}

void Session::tabColorSetByUser(bool set)
{
    _tabColorSetByUser = set;
}

bool Session::isTabColorSetByUser() const
{
    return _tabColorSetByUser;
}

void Session::silenceTimerDone()
{
    // FIXME: The idea here is that the notification popup will appear to tell the user than output from
    // the terminal has stopped and the popup will disappear when the user activates the session.
    //
    // This breaks with the addition of multiple views of a session.  The popup should disappear
    // when any of the views of the session becomes active

    // FIXME: Make message text for this notification and the activity notification more descriptive.
    if (!_monitorSilence) {
        setPendingNotification(Notification::Silence, false);
        return;
    }

    KNotification::event(hasFocus() ? QStringLiteral("Silence") : QStringLiteral("SilenceHidden"),
                         i18n("Silence in '%1' (Session '%2')", _displayTitle, _nameTitle),
                         QPixmap(),
                         QApplication::activeWindow(),
                         KNotification::CloseWhenWidgetActivated);
    setPendingNotification(Notification::Silence);
}

void Session::activityTimerDone()
{
    _notifiedActivity = false;
}

void Session::resetNotifications()
{
    static const Notification availableNotifications[] = {Activity, Silence, Bell};
    for (auto notification : availableNotifications) {
        setPendingNotification(notification, false);
    }
}

void Session::updateFlowControlState(bool suspended)
{
    if (suspended) {
        if (flowControlEnabled()) {
            for (TerminalDisplay *display : qAsConst(_views)) {
                if (display->flowControlWarningEnabled()) {
                    display->outputSuspended(true);
                }
            }
        }
    } else {
        for (TerminalDisplay *display : qAsConst(_views)) {
            display->outputSuspended(false);
        }
    }
}

void Session::onPrimaryScreenInUse(bool use)
{
    _isPrimaryScreen = use;
    Q_EMIT primaryScreenInUse(use);
}

bool Session::isPrimaryScreen()
{
    return _isPrimaryScreen;
}

void Session::sessionAttributeRequest(int id, uint terminator)
{
    switch (id) {
    case TextColor:
        // Get 'TerminalDisplay' (_view) foreground color
        Q_EMIT getForegroundColor(terminator);
        break;
    case BackgroundColor:
        // Get 'TerminalDisplay' (_view) background color
        Q_EMIT getBackgroundColor(terminator);
        break;
    }
}

void Session::onViewSizeChange(int /*height*/, int /*width*/)
{
    updateTerminalSize();
}

void Session::updateTerminalSize()
{
    int minLines = -1;
    int minColumns = -1;

    // minimum number of lines and columns that views require for
    // their size to be taken into consideration ( to avoid problems
    // with new view widgets which haven't yet been set to their correct size )
    const int VIEW_LINES_THRESHOLD = 2;
    const int VIEW_COLUMNS_THRESHOLD = 2;

    // select largest number of lines and columns that will fit in all visible views
    for (TerminalDisplay *view : qAsConst(_views)) {
        if (!view->isHidden() && view->lines() >= VIEW_LINES_THRESHOLD && view->columns() >= VIEW_COLUMNS_THRESHOLD) {
            minLines = (minLines == -1) ? view->lines() : qMin(minLines, view->lines());
            minColumns = (minColumns == -1) ? view->columns() : qMin(minColumns, view->columns());
            view->processFilters();
        }
    }

    // backend emulation must have a _terminal of at least 1 column x 1 line in size
    if (minLines > 0 && minColumns > 0) {
        _emulation->setImageSize(minLines, minColumns);
    }
}
void Session::updateWindowSize(int lines, int columns)
{
    Q_ASSERT(lines > 0 && columns > 0);
    _shellProcess->setWindowSi