1 files changed, 149 insertions, 0 deletions
diff --git a/src/gui/accessible/linux/dbusconnection.cpp b/src/gui/accessible/linux/dbusconnection.cpp
new file mode 100644
index 0000000000..10bd10927e
--- /dev/null
+++ b/src/gui/accessible/linux/dbusconnection.cpp
@@ -0,0 +1,149 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+
+
+#include "dbusconnection_p.h"
+
+#include <QtDBus/QDBusMessage>
+#include <QtDBus/QDBusServiceWatcher>
+#include <qdebug.h>
+
+#include <QDBusConnectionInterface>
+#include "bus_interface.h"
+
+#include <QtGui/qguiapplication.h>
+#include <qpa/qplatformnativeinterface.h>
+
+QT_BEGIN_NAMESPACE
+
+using namespace Qt::StringLiterals;
+
+/* note: do not change these to QStringLiteral;
+   we are unloaded before QtDBus is done using the strings.
+ */
+#define A11Y_SERVICE "org.a11y.Bus"_L1
+#define A11Y_PATH "/org/a11y/bus"_L1
+
+/*!
+    \class DBusConnection
+    \internal
+    \brief Connects to the accessibility dbus.
+
+    This is usually a different bus from the session bus.
+*/
+DBusConnection::DBusConnection(QObject *parent)
+    : QObject(parent), m_a11yConnection(QString()), m_enabled(false)
+{
+    // If the bus is explicitly set via env var it overrides everything else.
+    QByteArray addressEnv = qgetenv("AT_SPI_BUS_ADDRESS");
+    if (!addressEnv.isEmpty()) {
+        m_enabled = true;
+        connectA11yBus(QString::fromLocal8Bit(addressEnv));
+        return;
+    }
+
+    // Start monitoring if "org.a11y.Bus" is registered as DBus service.
+    QDBusConnection c = QDBusConnection::sessionBus();
+    if (!c.isConnected()) {
+        return;
+    }
+
+    dbusWatcher = new QDBusServiceWatcher(A11Y_SERVICE, c, QDBusServiceWatcher::WatchForRegistration, this);
+    connect(dbusWatcher, SIGNAL(serviceRegistered(QString)), this, SLOT(serviceRegistered()));
+
+    // If it is registered already, setup a11y right away
+    if (c.interface()->isServiceRegistered(A11Y_SERVICE))
+        serviceRegistered();
+
+    if (QGuiApplication::platformName().startsWith("xcb"_L1)) {
+        // In addition try if there is an xatom exposing the bus address, this allows applications run as root to work
+        QString address = getAddressFromXCB();
+        if (!address.isEmpty()) {
+            m_enabled = true;
+            connectA11yBus(address);
+        }
+    }
+}
+
+QString DBusConnection::getAddressFromXCB()
+{
+    QGuiApplication *app = qobject_cast<QGuiApplication *>(QCoreApplication::instance());
+    if (!app)
+        return QString();
+    QPlatformNativeInterface *platformNativeInterface = app->platformNativeInterface();
+    QByteArray *addressByteArray = reinterpret_cast<QByteArray*>(
+                platformNativeInterface->nativeResourceForIntegration(QByteArrayLiteral("AtspiBus")));
+    if (addressByteArray) {
+        QString address = QString::fromLatin1(*addressByteArray);
+        delete addressByteArray;
+        return address;
+    }
+    return QString();
+}
+
+// We have the a11y registry on the session bus.
+// Subscribe to updates about a11y enabled state.
+// Find out the bus address
+void DBusConnection::serviceRegistered()
+{
+    // listen to enabled changes
+    QDBusConnection c = QDBusConnection::sessionBus();
+    OrgA11yStatusInterface *a11yStatus = new OrgA11yStatusInterface(A11Y_SERVICE, A11Y_PATH, c, this);
+
+    //The variable was introduced because on some embedded platforms there are custom accessibility
+    //clients which don't set Status.ScreenReaderEnabled to true. The variable is also useful for
+    //debugging.
+    static const bool a11yAlwaysOn = qEnvironmentVariableIsSet("QT_LINUX_ACCESSIBILITY_ALWAYS_ON");
+
+    bool enabled = a11yAlwaysOn || a11yStatus->screenReaderEnabled() || a11yStatus->isEnabled();
+
+    if (enabled != m_enabled) {
+        m_enabled = enabled;
+        if (m_a11yConnection.isConnected()) {
+            emit enabledChanged(m_enabled);
+        } else {
+            QDBusConnection c = QDBusConnection::sessionBus();
+            QDBusMessage m = QDBusMessage::createMethodCall(A11Y_SERVICE, A11Y_PATH, A11Y_SERVICE,
+                                                            "GetAddress"_L1);
+            c.callWithCallback(m, this, SLOT(connectA11yBus(QString)), SLOT(dbusError(QDBusError)));
+        }
+    }
+
+    //    connect(a11yStatus, ); QtDbus doesn't support notifications for property changes yet
+}
+
+void DBusConnection::serviceUnregistered()
+{
+    emit enabledChanged(false);
+}
+
+void DBusConnection::connectA11yBus(const QString &address)
+{
+    if (address.isEmpty()) {
+        qWarning("Could not find Accessibility DBus address.");
+        return;
+    }
+    m_a11yConnection = QDBusConnection(QDBusConnection::connectToBus(address, "a11y"_L1));
+
+    if (m_enabled)
+        emit enabledChanged(true);
+}
+
+void DBusConnection::dbusError(const QDBusError &error)
+{
+    qWarning() << "Accessibility encountered a DBus error:" << error;
+}
+
+/*!
+  Returns the DBus connection that got established.
+  Or an invalid connection if not yet connected.
+*/
+QDBusConnection DBusConnection::connection() const
+{
+    return m_a11yConnection;
+}
+
+QT_END_NAMESPACE
+
+#include "moc_dbusconnection_p.cpp"