QBluetoothPermission: introduce fine-grained permissions

This commit introduces fine-grained Bluetooth permissions control to
the QBluetoothPermission class.
For now the fine-tuning of the permissions is only supported on
Android. On Apple enabling any of the permissions is equivalent to
requesting full Bluetooth control.

Task-number: QTBUG-109964
Change-Id: Ie7ac6577cf6a21419b73b33f8cf7e87bc3f8cf43
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

src/corelib/kernel/qpermissions.cpp

@@ -387,9 +387,60 @@ QT_PERMISSION_IMPL_COMMON(QMicrophonePermission)
 */
 
 QT_PERMISSION_IMPL_COMMON(QBluetoothPermission)
-    : u{} // stateless, atm
+    : u{ShortData{CommunicationMode::Default, {}}}
 {}
 
+/*!
+    \enum QBluetoothPermission::CommunicationMode
+    \since 6.6
+
+    This enum is used to control the allowed Bluetooth communication modes.
+
+    \value Access Allow this device to access other Bluetooth devices. This
+           includes scanning for nearby devices and connecting to them.
+    \value Advertise Allow other Bluetooth devices to discover this device.
+    \value Default This configuration is used by default.
+
+    \note The fine-grained permissions are currently supported only on
+    Android 12 and newer. On older Android versions, as well as on Apple
+    operating systems, any mode results in full Bluetooth access.
+
+    \note For now the \c Access mode on Android also requests the
+    \l {QLocationPermission::Precise}{precise location} permission.
+    This permission coupling may change in the future.
+*/
+
+/*!
+    \since 6.6
+
+    Sets the allowed Bluetooth communication modes to \a modes.
+
+    \note A default-constructed instance of \l {QBluetoothPermission::}
+    {CommunicationModes} has no sense, so an attempt to set such a mode will
+    raise a \c {qWarning()} and fall back to using the
+    \l {QBluetoothPermission::}{Default} mode.
+*/
+void QBluetoothPermission::setCommunicationModes(CommunicationModes modes)
+{
+    if (modes == CommunicationModes{}) {
+        qCWarning(lcPermissions, "QBluetoothPermission: trying to set an invalid empty mode. "
+                                 "Falling back to CommunicationMode::Default.");
+        u.data.mode = Default;
+    } else {
+        u.data.mode = static_cast<CommunicationMode>(modes.toInt());
+    }
+}
+
+/*!
+    \since 6.6
+
+    Returns the allowed Bluetooth communication modes.
+*/
+QBluetoothPermission::CommunicationModes QBluetoothPermission::communicationModes() const
+{
+    return u.data.mode;
+}
+
 /*!
     \class QLocationPermission
     \brief Access the user's location.

src/corelib/kernel/qpermissions.h

@@ -173,6 +173,32 @@ private:
 };
 Q_DECLARE_SHARED(QContactsPermission)
 
+class QBluetoothPermissionPrivate;
+class QBluetoothPermission
+{
+    Q_GADGET_EXPORT(Q_CORE_EXPORT)
+public:
+    enum CommunicationMode : quint8 {
+        Access = 0x01,
+        Advertise = 0x02,
+        Default = Access | Advertise,
+    };
+    Q_DECLARE_FLAGS(CommunicationModes, CommunicationMode)
+    Q_FLAG(CommunicationModes)
+
+    Q_CORE_EXPORT void setCommunicationModes(CommunicationModes modes);
+    Q_CORE_EXPORT CommunicationModes communicationModes() const;
+
+private:
+    struct ShortData {
+        CommunicationMode mode;
+        char reserved[sizeof(void*) - sizeof(mode)];
+    };
+    QT_PERMISSION(QBluetoothPermission)
+};
+Q_DECLARE_OPERATORS_FOR_FLAGS(QBluetoothPermission::CommunicationModes)
+Q_DECLARE_SHARED(QBluetoothPermission)
+
 #define Q_DECLARE_MINIMAL_PERMISSION(ClassName) \
     class ClassName##Private; \
     class ClassName \
@@ -184,7 +210,6 @@ Q_DECLARE_SHARED(QContactsPermission)
 
 Q_DECLARE_MINIMAL_PERMISSION(QCameraPermission)
 Q_DECLARE_MINIMAL_PERMISSION(QMicrophonePermission)
-Q_DECLARE_MINIMAL_PERMISSION(QBluetoothPermission)
 
 #undef QT_PERMISSION
 #undef Q_DECLARE_MINIMAL_PERMISSION

src/corelib/kernel/qpermissions_android.cpp

@@ -49,7 +49,7 @@ static QStringList nativeLocationPermission(const QLocationPermission &permissio
     return nativeLocationPermissionList;
 }
 
-static QStringList nativeBluetoothPermission()
+static QStringList nativeBluetoothPermission(const QBluetoothPermission &permission)
 {
     // See https://developer.android.com/guide/topics/connectivity/bluetooth/permissions
     // for the details.
@@ -64,10 +64,17 @@ static QStringList nativeBluetoothPermission()
     // strictly necessary for API Level >= 31. See QTBUG-112164.
     static QString fineLocation = u"android.permission.ACCESS_FINE_LOCATION"_s;
 
-    if (QtAndroidPrivate::androidSdkVersion() < 31)
+    if (QtAndroidPrivate::androidSdkVersion() < 31) {
         return {bluetoothGeneral, fineLocation};
-    else
+    } else {
-        return {bluetoothScan, bluetoothAdvertise, bluetoothConnect, fineLocation};
+        const auto modes = permission.communicationModes();
+        QStringList permissionList;
+        if (modes & QBluetoothPermission::Advertise)
+            permissionList << bluetoothAdvertise;
+        if (modes & QBluetoothPermission::Access)
+            permissionList << bluetoothScan << bluetoothConnect << fineLocation;
+        return permissionList;
+    }
 }
 
 static QStringList nativeStringsFromPermission(const QPermission &permission)
@@ -80,7 +87,7 @@ static QStringList nativeStringsFromPermission(const QPermission &permission)
     } else if (id == qMetaTypeId<QMicrophonePermission>()) {
         return { u"android.permission.RECORD_AUDIO"_s };
     } else if (id == qMetaTypeId<QBluetoothPermission>()) {
-        return nativeBluetoothPermission();
+        return nativeBluetoothPermission(*permission.value<QBluetoothPermission>());
     } else if (id == qMetaTypeId<QContactsPermission>()) {
         const auto readContactsString = u"android.permission.READ_CONTACTS"_s;
         switch (permission.value<QContactsPermission>()->accessMode()) {