File indexing completed on 2025-03-16 11:21:58

 /*
     KWin - the KDE window manager
     This file is part of the KDE project.
 
     SPDX-FileCopyrightText: 2019 Roman Gilg <subdiff@gmail.com>
     SPDX-FileCopyrightText: 2020 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
     SPDX-FileCopyrightText: 2022 David Edmundson <davidedmundson@kde.org>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 #include "xwaylandlauncher.h"
 
 #include <config-kwin.h>
 
 #include "xwayland_logging.h"
 #include "xwaylandsocket.h"
 
 #include "options.h"
 #include "wayland_server.h"
 
 #if KWIN_BUILD_NOTIFICATIONS
 #include <KLocalizedString>
 #include <KNotification>
 #endif
 
 #include <QAbstractEventDispatcher>
 #include <QDataStream>
 #include <QFile>
 #include <QHostInfo>
 #include <QRandomGenerator>
 #include <QScopeGuard>
 #include <QTimer>
 
 // system
 #include <cerrno>
 #include <cstring>
 #include <sys/socket.h>
 #include <unistd.h>
 
 namespace KWin
 {
 namespace Xwl
 {
 
 XwaylandLauncher::XwaylandLauncher(QObject *parent)
     : QObject(parent)
 {
     m_resetCrashCountTimer = new QTimer(this);
     m_resetCrashCountTimer->setSingleShot(true);
     connect(m_resetCrashCountTimer, &QTimer::timeout, this, &XwaylandLauncher::resetCrashCount);
 }
 
 XwaylandLauncher::~XwaylandLauncher()
 {
 }
 
 void XwaylandLauncher::setListenFDs(const QVector<int> &listenFds)
 {
     m_listenFds = listenFds;
 }
 
 void XwaylandLauncher::setDisplayName(const QString &displayName)
 {
     m_displayName = displayName;
 }
 
 void XwaylandLauncher::setXauthority(const QString &xauthority)
 {
     m_xAuthority = xauthority;
 }
 
 void XwaylandLauncher::start()
 {
     if (m_xwaylandProcess) {
         return;
     }
 
     if (!m_listenFds.isEmpty()) {
         Q_ASSERT(!m_displayName.isEmpty());
     } else {
         m_socket.reset(new XwaylandSocket(XwaylandSocket::OperationMode::CloseFdsOnExec));
         if (!m_socket->isValid()) {
             qFatal("Failed to establish X11 socket");
         }
         m_displayName = m_socket->name();
         m_listenFds = m_socket->fileDescriptors();
     }
 
     startInternal();
 }
 
 bool XwaylandLauncher::startInternal()
 {
     Q_ASSERT(!m_xwaylandProcess);
 
     QVector<int> fdsToClose;
     auto cleanup = qScopeGuard([&fdsToClose] {
         for (const int fd : std::as_const(fdsToClose)) {
             close(fd);
         }
     });
 
     int pipeFds[2];
     if (pipe(pipeFds) != 0) {
         qCWarning(KWIN_XWL, "Failed to create pipe to start Xwayland: %s", strerror(errno));
         Q_EMIT errorOccurred();
         return false;
     }
     fdsToClose << pipeFds[1];
 
     int sx[2];
     if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, sx) < 0) {
         qCWarning(KWIN_XWL, "Failed to open socket for XCB connection: %s", strerror(errno));
         Q_EMIT errorOccurred();
         return false;
     }
     int fd = dup(sx[1]);
     if (fd < 0) {
         qCWarning(KWIN_XWL, "Failed to open socket for XCB connection: %s", strerror(errno));
         Q_EMIT errorOccurred();
         return false;
     }
 
     const int waylandSocket = waylandServer()->createXWaylandConnection();
     if (waylandSocket == -1) {
         qCWarning(KWIN_XWL, "Failed to open socket for Xwayland server: %s", strerror(errno));
         Q_EMIT errorOccurred();
         return false;
     }
     const int wlfd = dup(waylandSocket);
     if (wlfd < 0) {
         qCWarning(KWIN_XWL, "Failed to open socket for Xwayland server: %s", strerror(errno));
         Q_EMIT errorOccurred();
         return false;
     }
 
     m_xcbConnectionFd = sx[0];
 
     QStringList arguments;
 
     arguments << m_displayName;
 
     if (!m_listenFds.isEmpty()) {
         // xauthority externally set and managed
         if (!m_xAuthority.isEmpty()) {
             arguments << QStringLiteral("-auth") << m_xAuthority;
         }
 
         for (int socket : std::as_const(m_listenFds)) {
             int dupSocket = dup(socket);
             fdsToClose << dupSocket;
 #if HAVE_XWAYLAND_LISTENFD
             arguments << QStringLiteral("-listenfd") << QString::number(dupSocket);
 #else
             arguments << QStringLiteral("-listen") << QString::number(dupSocket);
 #endif
         }
     }
 
     arguments << QStringLiteral("-displayfd") << QString::number(pipeFds[1]);
     arguments << QStringLiteral("-rootless");
     arguments << QStringLiteral("-wm") << QString::number(fd);
 
     m_xwaylandProcess = new QProcess(this);
     m_xwaylandProcess->setProcessChannelMode(QProcess::ForwardedErrorChannel);
     m_xwaylandProcess->setProgram(QStringLiteral("Xwayland"));
     QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
     env.insert("WAYLAND_SOCKET", QByteArray::number(wlfd));
     if (qEnvironmentVariableIsSet("KWIN_XWAYLAND_DEBUG")) {
         env.insert("WAYLAND_DEBUG", QByteArrayLiteral("1"));
     }
     m_xwaylandProcess->setProcessEnvironment(env);
     m_xwaylandProcess->setArguments(arguments);
     connect(m_xwaylandProcess, &QProcess::errorOccurred, this, &XwaylandLauncher::handleXwaylandError);
     connect(m_xwaylandProcess, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished),
             this, &XwaylandLauncher::handleXwaylandFinished);
 
     // When Xwayland starts writing the display name to displayfd, it is ready. Alternatively,
     // the Xwayland can send us the SIGUSR1 signal, but it's already reserved for VT hand-off.
     m_readyNotifier = new QSocketNotifier(pipeFds[0], QSocketNotifier::Read, this);
     connect(m_readyNotifier, &QSocketNotifier::activated, this, [this]() {
         maybeDestroyReadyNotifier();
         Q_EMIT started();
     });
 
     m_xwaylandProcess->start();
 
     return true;
 }
 
 void XwaylandLauncher::stop()
 {
     if (!m_xwaylandProcess) {
         return;
     }
 
     stopInternal();
 }
 
 QString XwaylandLauncher::displayName() const
 {
     return m_displayName;
 }
 
 QString XwaylandLauncher::xauthority() const
 {
     return m_xAuthority;
 }
 
 int XwaylandLauncher::xcbConnectionFd() const
 {
     return m_xcbConnectionFd;
 }
 
 QProcess *XwaylandLauncher::process() const
 {
     return m_xwaylandProcess;
 }
 
 void XwaylandLauncher::stopInternal()
 {
     Q_EMIT finished();
 
     maybeDestroyReadyNotifier();
     waylandServer()->destroyXWaylandConnection();
 
     // When the Xwayland process is finally terminated, the finished() signal will be emitted,
     // however we don't actually want to process it anymore. Furthermore, we also don't really
     // want to handle any errors that may occur during the teardown.
     if (m_xwaylandProcess->state() != QProcess::NotRunning) {
         disconnect(m_xwaylandProcess, nullptr, this, nullptr);
         m_xwaylandProcess->terminate();
         m_xwaylandProcess->waitForFinished(5000);
     }
     delete m_xwaylandProcess;
     m_xwaylandProcess = nullptr;
 }
 
 void XwaylandLauncher::restartInternal()
 {
     if (m_xwaylandProcess) {
         stopInternal();
     }
     startInternal();
 }
 
 void XwaylandLauncher::maybeDestroyReadyNotifier()
 {
     if (m_readyNotifier) {
         close(m_readyNotifier->socket());
 
         delete m_readyNotifier;
         m_readyNotifier = nullptr;
     }
 }
 
 void XwaylandLauncher::handleXwaylandFinished(int exitCode, QProcess::ExitStatus exitStatus)
 {
     qCDebug(KWIN_XWL) << "Xwayland process has quit with exit status:" << exitStatus << "exit code:" << exitCode;
 
 #if KWIN_BUILD_NOTIFICATIONS
     KNotification::event(QStringLiteral("xwaylandcrash"), i18n("Xwayland has crashed"));
 #endif
     m_resetCrashCountTimer->stop();
 
     switch (options->xwaylandCrashPolicy()) {
     case XwaylandCrashPolicy::Restart:
         if (++m_crashCount <= options->xwaylandMaxCrashCount()) {
             restartInternal();
             m_resetCrashCountTimer->start(std::chrono::minutes(10));
         } else {
             qCWarning(KWIN_XWL, "Stopping Xwayland server because it has crashed %d times "
                                 "over the past 10 minutes",
                       m_crashCount);
             stop();
         }
         break;
     case XwaylandCrashPolicy::Stop:
         stop();
         break;
     }
 }
 
 void XwaylandLauncher::resetCrashCount()
 {
     qCDebug(KWIN_XWL) << "Resetting the crash counter, its current value is" << m_crashCount;
     m_crashCount = 0;
 }
 
 void XwaylandLauncher::handleXwaylandError(QProcess::ProcessError error)
 {
     switch (error) {
     case QProcess::FailedToStart:
         qCWarning(KWIN_XWL) << "Xwayland process failed to start";
         return;
     case QProcess::Crashed:
         qCWarning(KWIN_XWL) << "Xwayland process crashed";
         break;
     case QProcess::Timedout:
         qCWarning(KWIN_XWL) << "Xwayland operation timed out";
         break;
     case QProcess::WriteError:
     case QProcess::ReadError:
         qCWarning(KWIN_XWL) << "An error occurred while communicating with Xwayland";
         break;
     case QProcess::UnknownError:
         qCWarning(KWIN_XWL) << "An unknown error has occurred in Xwayland";
         break;
     }
     Q_EMIT errorOccurred();
 }
 
 }
 }