Merge remote-tracking branch 'gerrit/dev' into btlebtle

Change-Id: Id7698ec157a4e06296bcc27d48aaa8325dd3c23a

8 files changed, 466 insertions, 137 deletions

diff --git a/src/bluetooth/osx/osxbt.pri b/src/bluetooth/osx/osxbt.pri
index 13187e4f..b7ac0535 100644
--- a/src/bluetooth/osx/osxbt.pri
+++ b/src/bluetooth/osx/osxbt.pri
@@ -1,6 +1,9 @@
 SOURCES += osx/uistrings.cpp osx/osxbtnotifier.cpp
-PRIVATE_HEADERS += osx/uistrings_p.h
-//QMAKE_CXXFLAGS_WARN_ON += -Wno-nullability-completeness
+PRIVATE_HEADERS += osx/uistrings_p.h \
+                   osx/osxbtgcdtimer_p.h
+
+OBJECTIVE_SOURCES += osx/osxbtgcdtimer.mm
+#QMAKE_CXXFLAGS_WARN_ON += -Wno-nullability-completeness
 
 CONFIG(osx) {
     PRIVATE_HEADERS += osx/osxbtutility_p.h \
diff --git a/src/bluetooth/osx/osxbtcentralmanager.mm b/src/bluetooth/osx/osxbtcentralmanager.mm
index 70473f1f..9254bd98 100644
--- a/src/bluetooth/osx/osxbtcentralmanager.mm
+++ b/src/bluetooth/osx/osxbtcentralmanager.mm
@@ -79,8 +79,21 @@ NSUInteger qt_countGATTEntries(CBService *service)
     return n;
 }
 
+ObjCStrongReference<NSError> qt_timeoutNSError(OperationTimeout type)
+{
+    // For now we do not provide details, since nobody is using this NSError
+    // after all (except callbacks checking if an operation was successful
+    // or not).
+    Q_ASSERT(type != OperationTimeout::none);
+    Q_UNUSED(type)
+    NSError *nsError = [[NSError alloc] initWithDomain:CBErrorDomain
+                                        code:CBErrorOperationCancelled
+                                        userInfo:nil];
+    return ObjCStrongReference<NSError>(nsError, false /*do not retain, done already*/);
 }
 
+} // namespace OSXBluetooth
+
 QT_END_NAMESPACE
 
 
@@ -115,9 +128,11 @@ QT_END_NAMESPACE
 
 - (id)initWith:(OSXBluetooth::LECBManagerNotifier *)aNotifier
 {
+    using namespace OSXBluetooth;
+
     if (self = [super init]) {
         manager = nil;
-        managerState = OSXBluetooth::CentralManagerIdle;
+        managerState = CentralManagerIdle;
         disconnectPending = false;
         peripheral = nil;
         notifier = aNotifier;
@@ -125,6 +140,17 @@ QT_END_NAMESPACE
         lastValidHandle = 0;
         requestPending = false;
         currentReadHandle = 0;
+        timeoutType = OperationTimeout::none;
+
+        if (Q_UNLIKELY(!qEnvironmentVariableIsEmpty("BLUETOOTH_GATT_TIMEOUT"))) {
+            bool ok = false;
+            const int value = qEnvironmentVariableIntValue("BLUETOOTH_GATT_TIMEOUT", &ok);
+            if (ok && value >= 0)
+                timeoutMS = value;
+        }
+
+        if (!timeoutMS)
+            timeoutMS = 20000;
     }
 
     return self;
@@ -153,6 +179,63 @@ QT_END_NAMESPACE
     [super dealloc];
 }
 
+- (void)watchAfter:(id)object timeout:(OSXBluetooth::OperationTimeout)type
+{
+    using namespace OSXBluetooth;
+
+    objectUnderWatch = object;
+    timeoutType = type;
+    [timeoutWatchdog cancelTimer];
+    timeoutWatchdog.reset([[GCDTimerObjC alloc] initWithDelegate:self]);
+    [timeoutWatchdog startWithTimeout:timeoutMS step:200];
+}
+
+- (void)stopWatchdog
+{
+    [timeoutWatchdog cancelTimer];
+    objectUnderWatch = nil;
+    timeoutType = OSXBluetooth::OperationTimeout::none;
+}
+
+- (void)timeout
+{
+    using namespace OSXBluetooth;
+
+    Q_ASSERT(objectUnderWatch);
+    NSLog(@"Timeout caused by: %@", objectUnderWatch);
+    const ObjCStrongReference<NSError> nsError(qt_timeoutNSError(timeoutType));
+    switch (timeoutType) {
+    case OperationTimeout::serviceDiscovery:
+        qCWarning(QT_BT_OSX, "Timeout in services discovery");
+        [self peripheral:peripheral didDiscoverServices:nsError];
+        break;
+    case OperationTimeout::includedServicesDiscovery:
+        qCWarning(QT_BT_OSX, "Timeout in included services discovery");
+        [self peripheral:peripheral didDiscoverIncludedServicesForService:objectUnderWatch error:nsError];
+        break;
+    case OperationTimeout::characteristicsDiscovery:
+        qCWarning(QT_BT_OSX, "Timeout in characteristics discovery");
+        [self peripheral:peripheral didDiscoverCharacteristicsForService:objectUnderWatch error:nsError];
+        break;
+    case OperationTimeout::characteristicRead:
+        qCWarning(QT_BT_OSX, "Timeout while reading a characteristic");
+        [self peripheral:peripheral didUpdateValueForCharacteristic:objectUnderWatch error:nsError];
+        break;
+    case OperationTimeout::descriptorsDiscovery:
+        qCWarning(QT_BT_OSX, "Timeout in descriptors discovery");
+        [self peripheral:peripheral didDiscoverDescriptorsForCharacteristic:objectUnderWatch error:nsError];
+        break;
+    case OperationTimeout::descriptorRead:
+        qCWarning(QT_BT_OSX, "Timeout while reading a descriptor");
+        [self peripheral:peripheral didUpdateValueForDescriptor:objectUnderWatch error:nsError];
+        break;
+    case OperationTimeout::characteristicWrite:
+        qCWarning(QT_BT_OSX, "Timeout while writing a characteristic with response");
+        [self peripheral:peripheral didWriteValueForCharacteristic:objectUnderWatch error:nsError];
+    default:;
+    }
+}
+
 - (void)connectToDevice:(const QBluetoothUuid &)aDeviceUuid
 {
     disconnectPending = false; // Cancel the previous disconnect if any.
@@ -235,10 +318,11 @@ QT_END_NAMESPACE
 
 - (void)connectToPeripheral
 {
+    using namespace OSXBluetooth;
+
     Q_ASSERT_X(manager, Q_FUNC_INFO, "invalid central manager (nil)");
     Q_ASSERT_X(peripheral, Q_FUNC_INFO, "invalid peripheral (nil)");
-    Q_ASSERT_X(managerState == OSXBluetooth::CentralManagerIdle,
-               Q_FUNC_INFO, "invalid state");
+    Q_ASSERT_X(managerState == CentralManagerIdle, Q_FUNC_INFO, "invalid state");
 
     // The state is still the same - connecting.
     if ([self isConnected]) {
@@ -247,7 +331,7 @@ QT_END_NAMESPACE
             emit notifier->connected();
     } else {
         qCDebug(QT_BT_OSX) << "trying to connect";
-        managerState = OSXBluetooth::CentralManagerConnecting;
+        managerState = CentralManagerConnecting;
         [manager connectPeripheral:peripheral options:nil];
     }
 }
@@ -292,9 +376,10 @@ QT_END_NAMESPACE
 
 - (void)discoverServices
 {
+    using namespace OSXBluetooth;
+
     Q_ASSERT_X(peripheral, Q_FUNC_INFO, "invalid peripheral (nil)");
-    Q_ASSERT_X(managerState == OSXBluetooth::CentralManagerIdle,
-               Q_FUNC_INFO, "invalid state");
+    Q_ASSERT_X(managerState == CentralManagerIdle, Q_FUNC_INFO, "invalid state");
 
     // From Apple's docs:
     //
@@ -304,7 +389,8 @@ QT_END_NAMESPACE
     //
     // ... but we'd like to have them all:
     [peripheral setDelegate:self];
-    managerState = OSXBluetooth::CentralManagerDiscovering;
+    managerState = CentralManagerDiscovering;
+    [self watchAfter:peripheral timeout:OperationTimeout::serviceDiscovery];
     [peripheral discoverServices:nil];
 }
 
@@ -333,6 +419,7 @@ QT_END_NAMESPACE
         CBService *const s = [services objectAtIndex:currentService];
         [visitedServices addObject:s];
         managerState = CentralManagerDiscovering;
+        [self watchAfter:s timeout:OperationTimeout::includedServicesDiscovery];
         [peripheral discoverIncludedServices:nil forService:s];
     }
 }
@@ -359,6 +446,7 @@ QT_END_NAMESPACE
 
     if (CBService *const service = [self serviceForUUID:serviceUuid]) {
         servicesToDiscoverDetails.append(serviceUuid);
+        [self watchAfter:service timeout:OperationTimeout::characteristicsDiscovery];
         [peripheral discoverCharacteristics:nil forService:service];
         return;
     }
@@ -366,10 +454,8 @@ QT_END_NAMESPACE
     qCWarning(QT_BT_OSX) << "unknown service uuid"
                          << serviceUuid;
 
-    if (notifier) {
-        emit notifier->CBManagerError(serviceUuid,
-                       QLowEnergyService::UnknownError);
-    }
+    if (notifier)
+        emit notifier->CBManagerError(serviceUuid, QLowEnergyService::UnknownError);
 }
 
 - (void)readCharacteristics:(CBService *)service
@@ -391,8 +477,10 @@ QT_END_NAMESPACE
 
     NSArray *const cs = service.characteristics;
     for (CBCharacteristic *c in cs) {
-        if (c.properties & CBCharacteristicPropertyRead)
+        if (c.properties & CBCharacteristicPropertyRead) {
+            [self watchAfter:c timeout:OperationTimeout::characteristicRead];
             return [peripheral readValueForCharacteristic:c];
+        }
     }
 
     // No readable properties? Discover descriptors then:
@@ -418,15 +506,18 @@ QT_END_NAMESPACE
         [self serviceDetailsDiscoveryFinished:service];
     } else {
         // Start from 0 and continue in the callback.
-        [peripheral discoverDescriptorsForCharacteristic:[service.characteristics objectAtIndex:0]];
+        CBCharacteristic *ch = [service.characteristics objectAtIndex:0];
+        [self watchAfter:ch timeout:OperationTimeout::descriptorsDiscovery];
+        [peripheral discoverDescriptorsForCharacteristic:ch];
     }
 }
 
 - (void)readDescriptors:(CBService *)service
 {
+    using namespace OSXBluetooth;
+
     Q_ASSERT_X(service, Q_FUNC_INFO, "invalid service (nil)");
-    Q_ASSERT_X(managerState != OSXBluetooth::CentralManagerUpdating,
-               Q_FUNC_INFO, "invalid state");
+    Q_ASSERT_X(managerState != CentralManagerUpdating, Q_FUNC_INFO, "invalid state");
     Q_ASSERT_X(peripheral, Q_FUNC_INFO, "invalid peripheral (nil)");
 
     QT_BT_MAC_AUTORELEASEPOOL;
@@ -435,8 +526,11 @@ QT_END_NAMESPACE
     // We can never be here if we have no characteristics.
     Q_ASSERT_X(cs && cs.count, Q_FUNC_INFO, "invalid service");
     for (CBCharacteristic *c in cs) {
-        if (c.descriptors && c.descriptors.count)
-            return [peripheral readValueForDescriptor:[c.descriptors objectAtIndex:0]];
+        if (c.descriptors && c.descriptors.count) {
+            CBDescriptor *desc = [c.descriptors objectAtIndex:0];
+            [self watchAfter:desc timeout:OperationTimeout::descriptorRead];
+            return [peripheral readValueForDescriptor:desc];
+        }
     }
 
     // No descriptors to read, done.
@@ -571,6 +665,8 @@ QT_END_NAMESPACE
 
         requestPending = true;
         currentReadHandle = request.handle;
+        // Timeouts: for now, we do not alert timeoutWatchdog - never had such
+        // bug reports and after all a read timeout can be handled externally.
         [peripheral readValueForCharacteristic:charMap[request.handle]];
     } else {
         if (!descMap.contains(request.handle)) {
@@ -581,6 +677,7 @@ QT_END_NAMESPACE
 
         requestPending = true;
         currentReadHandle = request.handle;
+        // Timeouts: see the comment above (CharRead).
         [peripheral readValueForDescriptor:descMap[request.handle]];
     }
 }
@@ -657,6 +754,7 @@ QT_END_NAMESPACE
                     return [self performNextRequest];
 
                 requestPending = true;
+                [self watchAfter:characteristic timeout:OperationTimeout::characteristicWrite];
                 [peripheral writeValue:data.data() forCharacteristic:characteristic
                             type:CBCharacteristicWriteWithResponse];
             } else {
@@ -1021,6 +1119,7 @@ QT_END_NAMESPACE
     charMap.clear();
     descMap.clear();
     currentReadHandle = 0;
+    [self stopWatchdog];
     // TODO: also serviceToVisit/VisitNext and visitedServices ?
 }
 
@@ -1030,6 +1129,9 @@ QT_END_NAMESPACE
 {
     using namespace OSXBluetooth;
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunguarded-availability-new"
+
     const auto state = central.state;
 #if QT_IOS_PLATFORM_SDK_EQUAL_OR_ABOVE(__IPHONE_10_0) || QT_OSX_PLATFORM_SDK_EQUAL_OR_ABOVE(__MAC_10_13)
     if (state == CBManagerStateUnknown
@@ -1072,12 +1174,14 @@ QT_END_NAMESPACE
 #else
     if (state == CBCentralManagerStatePoweredOff) {
 #endif
-        managerState = CentralManagerIdle;
+
         if (managerState == CentralManagerUpdating) {
+            managerState = CentralManagerIdle;
             // I've seen this instead of Unsupported on OS X.
             if (notifier)
                 emit notifier->LEnotSupported();
         } else {
+            managerState = CentralManagerIdle;
             // TODO: we need a better error +
             // what will happen if later the state changes to PoweredOn???
             if (notifier)
@@ -1099,6 +1203,8 @@ QT_END_NAMESPACE
         // We actually handled all known states, but .. Core Bluetooth can change?
         Q_ASSERT_X(0, Q_FUNC_INFO, "invalid centra's state");
     }
+
+#pragma clang diagnostic pop
 }
 
 - (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)aPeripheral
@@ -1162,10 +1268,16 @@ QT_END_NAMESPACE
     Q_UNUSED(aPeripheral)
 
     if (managerState != OSXBluetooth::CentralManagerDiscovering) {
-        // Canceled by -disconnectFromDevice.
+        // Canceled by -disconnectFromDevice, or as a result of a timeout.
+        return;
+    }
+
+    if (objectUnderWatch != aPeripheral) {
+        // Timed out.
         return;
     }
 
+    [self stopWatchdog];
     managerState = OSXBluetooth::CentralManagerIdle;
 
     if (error) {
@@ -1173,9 +1285,9 @@ QT_END_NAMESPACE
         // TODO: better error mapping required.
         if (notifier)
             emit notifier->CBManagerError(QLowEnergyController::UnknownError);
-    } else {
-        [self discoverIncludedServices];
     }
+
+    [self discoverIncludedServices];
 }
 
 
@@ -1191,10 +1303,16 @@ QT_END_NAMESPACE
         return;
     }
 
+    if (service != objectUnderWatch) {
+        // Timed out.
+        return;
+    }
+
     QT_BT_MAC_AUTORELEASEPOOL;
 
     Q_ASSERT_X(peripheral, Q_FUNC_INFO, "invalid peripheral (nil)");
 
+    [self stopWatchdog];
     managerState = CentralManagerIdle;
 
     if (error) {
@@ -1217,6 +1335,7 @@ QT_END_NAMESPACE
             // Continue with discovery ...
             [visitedServices addObject:s];
             managerState = CentralManagerDiscovering;
+            [self watchAfter:s timeout:OperationTimeout::includedServicesDiscovery];
             return [peripheral discoverIncludedServices:nil forService:s];
         }
     }
@@ -1232,6 +1351,7 @@ QT_END_NAMESPACE
             if (![visitedServices containsObject:s]) {
                 [visitedServices addObject:s];
                 managerState = CentralManagerDiscovering;
+                [self watchAfter:s timeout:OperationTimeout::includedServicesDiscovery];
                 return [peripheral discoverIncludedServices:nil forService:s];
             }
         }
@@ -1260,6 +1380,13 @@ QT_END_NAMESPACE
         return;
     }
 
+    if (service != objectUnderWatch) {
+        // Timed out already?
+        return;
+    }
+
+    [self stopWatchdog];
+
     using namespace OSXBluetooth;
 
     Q_ASSERT_X(managerState != CentralManagerUpdating, Q_FUNC_INFO, "invalid state");
@@ -1269,9 +1396,9 @@ QT_END_NAMESPACE
         // We did not discover any characteristics and can not discover descriptors,
         // inform our delegate (it will set a service state also).
         emit notifier->CBManagerError(qt_uuid(service.UUID), QLowEnergyController::UnknownError);
-    } else {
-        [self readCharacteristics:service];
     }
+
+    [self readCharacteristics:service];
 }
 
 - (void)peripheral:(CBPeripheral *)aPeripheral
@@ -1285,6 +1412,10 @@ QT_END_NAMESPACE
         return;
     }
 
+    const bool readMatch = characteristic == objectUnderWatch;
+    if (readMatch)
+        [self stopWatchdog];
+
     using namespace OSXBluetooth;
 
     Q_ASSERT_X(managerState != CentralManagerUpdating, Q_FUNC_INFO, "invalid state");
@@ -1311,13 +1442,17 @@ QT_END_NAMESPACE
     }
 
     if (isDetailsDiscovery) {
-        // Test if we have any other characteristic to read yet.
-        CBCharacteristic *const next = [self nextCharacteristicForService:characteristic.service
-                                             startingFrom:characteristic properties:CBCharacteristicPropertyRead];
-        if (next)
-            [peripheral readValueForCharacteristic:next];
-        else
-            [self discoverDescriptors:characteristic.service];
+        if (readMatch) {
+            // Test if we have any other characteristic to read yet.
+            CBCharacteristic *const next = [self nextCharacteristicForService:characteristic.service
+                                                 startingFrom:characteristic properties:CBCharacteristicPropertyRead];
+            if (next) {
+                [self watchAfter:next timeout:OperationTimeout::characteristicRead];
+                [peripheral readValueForCharacteristic:next];
+            } else {
+                [self discoverDescriptors:characteristic.service];
+            }
+        }
     } else {
         // This is (probably) the result of update notification.
         // It's very possible we can have an invalid handle here (0) -
@@ -1360,6 +1495,11 @@ QT_END_NAMESPACE
 
     QT_BT_MAC_AUTORELEASEPOOL;
 
+    if (characteristic != objectUnderWatch)
+        return;
+
+    [self stopWatchdog];
+
     using namespace OSXBluetooth;
 
     if (error) {
@@ -1370,10 +1510,12 @@ QT_END_NAMESPACE
     // Do we have more characteristics on this service to discover descriptors?
     CBCharacteristic *const next = [self nextCharacteristicForService:characteristic.service
                                          startingFrom:characteristic];
-    if (next)
+    if (next) {
+        [self watchAfter:next timeout:OperationTimeout::descriptorsDiscovery];
         [peripheral discoverDescriptorsForCharacteristic:next];
-    else
+    } else {
         [self readDescriptors:characteristic.service];
+    }
 }
 
 - (void)peripheral:(CBPeripheral *)aPeripheral
@@ -1391,6 +1533,11 @@ QT_END_NAMESPACE
 
     QT_BT_MAC_AUTORELEASEPOOL;
 
+    if (descriptor != objectUnderWatch)
+        return;
+
+    [self stopWatchdog];
+
     using namespace OSXBluetooth;
 
     CBService *const service = descriptor.characteristic.service;
@@ -1417,6 +1564,7 @@ QT_END_NAMESPACE
         CBDescriptor *const next = [self nextDescriptorForCharacteristic:descriptor.characteristic
                                          startingFrom:descriptor];
         if (next) {
+            [self watchAfter:next timeout:OperationTimeout::descriptorRead];
             [peripheral readValueForDescriptor:next];
         } else {
             // We either have to read a value for a next descriptor
@@ -1426,8 +1574,11 @@ QT_END_NAMESPACE
             CBCharacteristic *nextCh = [self nextCharacteristicForService:ch.service
                                              startingFrom:ch];
             while (nextCh) {
-                if (nextCh.descriptors && nextCh.descriptors.count)
-                    return [peripheral readValueForDescriptor:[nextCh.descriptors objectAtIndex:0]];
+                if (nextCh.descriptors && nextCh.descriptors.count) {
+                    CBDescriptor *desc = [nextCh.descriptors objectAtIndex:0];
+                    [self watchAfter:desc timeout:OperationTimeout::descriptorRead];
+                    return [peripheral readValueForDescriptor:desc];
+                }
 
                 nextCh = [self nextCharacteristicForService:ch.service
                                startingFrom:nextCh];
@@ -1474,6 +1625,10 @@ QT_END_NAMESPACE
 
     QT_BT_MAC_AUTORELEASEPOOL;
 
+    if (characteristic != objectUnderWatch)
+        return;
+
+    [self stopWatchdog];
     requestPending = false;
 
 
@@ -1569,9 +1724,10 @@ QT_END_NAMESPACE
     if (notifier) {
         notifier->disconnect();
         notifier->deleteLater();
-        notifier = 0;
+        notifier = nullptr;
     }
 
+    [self stopWatchdog];
     [self disconnectFromDevice];
 }
 
diff --git a/src/bluetooth/osx/osxbtcentralmanager_p.h b/src/bluetooth/osx/osxbtcentralmanager_p.h
index 697d922c..e172d874 100644
--- a/src/bluetooth/osx/osxbtcentralmanager_p.h
+++ b/src/bluetooth/osx/osxbtcentralmanager_p.h
@@ -53,6 +53,7 @@
 
 #include "qlowenergycontroller.h"
 #include "qlowenergyservice.h"
+#include "osxbtgcdtimer_p.h"
 #include "qbluetoothuuid.h"
 #include "osxbtutility_p.h"
 #include "osxbluetooth_p.h"
@@ -86,6 +87,18 @@ enum CentralManagerState
     CentralManagerDisconnecting
 };
 
+enum class OperationTimeout
+{
+    none,
+    serviceDiscovery,
+    includedServicesDiscovery,
+    characteristicsDiscovery,
+    characteristicRead,
+    descriptorsDiscovery,
+    descriptorRead,
+    characteristicWrite
+};
+
 // In Qt we work with handles and UUIDs. Core Bluetooth
 // has NSArrays (and nested NSArrays inside servces/characteristics).
 // To simplify a navigation, I need a simple way to map from a handle
@@ -132,7 +145,9 @@ typedef QHash<NSObject *, QByteArray> ValueHash;
 
 QT_END_NAMESPACE
 
-@interface QT_MANGLE_NAMESPACE(OSXBTCentralManager) : NSObject<CBCentralManagerDelegate, CBPeripheralDelegate>
+@interface QT_MANGLE_NAMESPACE(OSXBTCentralManager) : NSObject<CBCentralManagerDelegate,
+                                                               CBPeripheralDelegate,
+                                                               QT_MANGLE_NAMESPACE(GCDTimerDelegate)>
 {
 @private
     CBCentralManager *manager;
@@ -166,6 +181,12 @@ QT_END_NAMESPACE
     QT_PREPEND_NAMESPACE(QLowEnergyHandle) currentReadHandle;
 
     QT_PREPEND_NAMESPACE(OSXBluetooth)::ValueHash valuesToWrite;
+
+    qint64 timeoutMS;
+    id objectUnderWatch;
+    QT_PREPEND_NAMESPACE(OSXBluetooth)::OperationTimeout timeoutType;
+    QT_PREPEND_NAMESPACE(OSXBluetooth)::GCDTimer timeoutWatchdog;
+
 @public
     CBPeripheral *peripheral;
 }
diff --git a/src/bluetooth/osx/osxbtgcdtimer.mm b/src/bluetooth/osx/osxbtgcdtimer.mm
new file mode 100644
index 00000000..095f8680
--- /dev/null
+++ b/src/bluetooth/osx/osxbtgcdtimer.mm
@@ -0,0 +1,111 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtBluetooth module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "osxbtgcdtimer_p.h"
+#include "osxbtutility_p.h"
+
+#include <QtCore/qdebug.h>
+
+#include <algorithm>
+
+@implementation QT_MANGLE_NAMESPACE(OSXBTGCDTimer)
+
+- (instancetype)initWithDelegate:(id<QT_MANGLE_NAMESPACE(GCDTimerDelegate)>)delegate
+{
+    if (self = [super init]) {
+        timeoutHandler = delegate;
+        timeoutMS = 0;
+        timeoutStepMS = 0;
+        cancelled = false;
+    }
+    return self;
+}
+
+- (void)startWithTimeout:(qint64)ms step:(qint64)stepMS
+{
+    Q_ASSERT(!timeoutMS && !timeoutStepMS);
+    Q_ASSERT(!cancelled);
+
+    if (!timeoutHandler) {
+        // Nobody to report timeout to, no need to start any task then.
+        return;
+    }
+
+    if (ms <= 0 || stepMS <= 0) {
+        qCWarning(QT_BT_OSX, "Invalid timeout/step parameters");
+        return;
+    }
+
+    timeoutMS = ms;
+    timeoutStepMS = stepMS;
+    timer.start();
+
+    [self handleTimeout];
+}
+
+- (void)handleTimeout
+{
+    if (cancelled)
+        return;
+
+    const qint64 elapsed = timer.elapsed();
+    if (elapsed >= timeoutMS) {
+        [timeoutHandler timeout];
+    } else {
+        using namespace QT_PREPEND_NAMESPACE(OSXBluetooth);
+        // Re-schedule:
+        dispatch_queue_t leQueue(qt_LE_queue());
+        Q_ASSERT(leQueue);
+        const qint64 timeChunkMS = std::min(timeoutMS - elapsed, timeoutStepMS);
+        dispatch_after(dispatch_time(DISPATCH_TIME_NOW,
+                                     int64_t(timeChunkMS / 1000. * NSEC_PER_SEC)),
+                                     leQueue,
+                                     ^{
+                                           [self handleTimeout];
+                                      });
+    }
+}
+
+- (void)cancelTimer
+{
+    cancelled = true;
+    timeoutHandler = nil;
+}
+
+@end
diff --git a/src/bluetooth/osx/osxbtgcdtimer_p.h b/src/bluetooth/osx/osxbtgcdtimer_p.h
new file mode 100644
index 00000000..007a004b
--- /dev/null
+++ b/src/bluetooth/osx/osxbtgcdtimer_p.h
@@ -0,0 +1,94 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtBluetooth module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef OSXBTGCDTIMER_P_H
+#define OSXBTGCDTIMER_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "osxbtutility_p.h"
+
+#include <QtCore/qelapsedtimer.h>
+#include <QtCore/qglobal.h>
+
+#include <Foundation/Foundation.h>
+
+@protocol QT_MANGLE_NAMESPACE(GCDTimerDelegate)
+@required
+- (void)timeout;
+@end
+
+@interface QT_MANGLE_NAMESPACE(OSXBTGCDTimer) : NSObject {
+@private
+    qint64 timeoutMS;
+    qint64 timeoutStepMS;
+    QT_PREPEND_NAMESPACE(QElapsedTimer) timer;
+    id<QT_MANGLE_NAMESPACE(GCDTimerDelegate)> timeoutHandler;
+    bool cancelled;
+}
+
+- (instancetype)initWithDelegate:(id<QT_MANGLE_NAMESPACE(GCDTimerDelegate)>)delegate;
+- (void)startWithTimeout:(qint64)ms step:(qint64)stepMS;
+- (void)handleTimeout;
+- (void)cancelTimer;
+
+@end
+
+QT_BEGIN_NAMESPACE
+
+namespace OSXBluetooth {
+
+using GCDTimerObjC = QT_MANGLE_NAMESPACE(OSXBTGCDTimer);
+using GCDTimer = ObjCScopedPointer<GCDTimerObjC>;
+
+}
+
+QT_END_NAMESPACE
+
+#endif // OSXBTGCDTIMER_P_H
+
diff --git a/src/bluetooth/osx/osxbtledeviceinquiry.mm b/src/bluetooth/osx/osxbtledeviceinquiry.mm
index 7a516dd4..2cece15b 100644
--- a/src/bluetooth/osx/osxbtledeviceinquiry.mm
+++ b/src/bluetooth/osx/osxbtledeviceinquiry.mm
@@ -65,9 +65,7 @@ QBluetoothUuid qt_uuid(NSUUID *nsUuid)
 }
 
 const int timeStepMS = 100;
-
 const int powerOffTimeoutMS = 30000;
-const qreal powerOffTimeStepS = 30. / 100.;
 
 struct AdvertisementData {
     // That's what CoreBluetooth has:
@@ -115,14 +113,6 @@ QT_END_NAMESPACE
 
 QT_USE_NAMESPACE
 
-@interface QT_MANGLE_NAMESPACE(OSXBTLEDeviceInquiry) (PrivateAPI) <CBCentralManagerDelegate>
-// These two methods are scheduled with a small time step
-// within a given timeout, they either re-schedule
-// themselves or emit a signal/stop some operation.
-- (void)stopScan;
-- (void)handlePoweredOff;
-@end
-
 @implementation QT_MANGLE_NAMESPACE(OSXBTLEDeviceInquiry)
 
 -(id)initWithNotifier:(LECBManagerNotifier *)aNotifier
@@ -153,60 +143,22 @@ QT_USE_NAMESPACE
     [super dealloc];
 }
 
-- (void)stopScan
+- (void)timeout
 {
-    using namespace OSXBluetooth;
-
-    // We never schedule stopScan if there is no timeout:
-    Q_ASSERT(inquiryTimeoutMS > 0);
-
     if (internalState == InquiryActive) {
-        const int elapsed = scanTimer.elapsed();
-        if (elapsed >= inquiryTimeoutMS) {
-            [manager stopScan];
-            [manager setDelegate:nil];
-            internalState = InquiryFinished;
-            Q_ASSERT(notifier);
-            emit notifier->discoveryFinished();
-        } else {
-            // Re-schedule 'stopScan':
-            dispatch_queue_t leQueue(qt_LE_queue());
-            Q_ASSERT(leQueue);
-            const int timeChunkMS = std::min(inquiryTimeoutMS - elapsed, timeStepMS);
-            dispatch_after(dispatch_time(DISPATCH_TIME_NOW,
-                                         int64_t(timeChunkMS / 1000. * NSEC_PER_SEC)),
-                                         leQueue,
-                                         ^{
-                                               [self stopScan];
-                                          });
-        }
-    }
-}
-
-- (void)handlePoweredOff
-{
-    // This is interesting on iOS only, where
-    // the system shows an alert asking to enable
-    // Bluetooth in the 'Settings' app. If not done yet (after 30
-    // seconds) - we consider it an error.
-    using namespace OSXBluetooth;
-
-    if (internalState == InquiryStarting) {
-        if (errorTimer.elapsed() >= powerOffTimeoutMS) {
-            [manager setDelegate:nil];
-            internalState = ErrorPoweredOff;
-            Q_ASSERT(notifier);
-            emit notifier->CBManagerError(QBluetoothDeviceDiscoveryAgent::PoweredOffError);
-        } else {
-            dispatch_queue_t leQueue(qt_LE_queue());
-            Q_ASSERT(leQueue);
-            dispatch_after(dispatch_time(DISPATCH_TIME_NOW,
-                                         (int64_t)(powerOffTimeStepS * NSEC_PER_SEC)),
-                                         leQueue,
-                                         ^{
-                                              [self handlePoweredOff];
-                                          });
-        }
+        [manager stopScan];
+        [manager setDelegate:nil];
+        internalState = InquiryFinished;
+        Q_ASSERT(notifier);
+        emit notifier->discoveryFinished();
+    } else if (internalState == InquiryStarting) {
+        // This is interesting on iOS only, where the system shows an alert
+        // asking to enable Bluetooth in the 'Settings' app. If not done yet
+        // (after 30 seconds) - we consider this as an error.
+        [manager setDelegate:nil];
+        internalState = ErrorPoweredOff;
+        Q_ASSERT(notifier);
+        emit notifier->CBManagerError(QBluetoothDeviceDiscoveryAgent::PoweredOffError);
     }
 }
 
@@ -220,6 +172,9 @@ QT_USE_NAMESPACE
 
 - (void)centralManagerDidUpdateState:(CBCentralManager *)central
 {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunguarded-availability-new"
+
     if (central != manager)
         return;
 
@@ -230,9 +185,6 @@ QT_USE_NAMESPACE
 
     using namespace OSXBluetooth;
 
-    dispatch_queue_t leQueue(qt_LE_queue());
-    Q_ASSERT(leQueue);
-
     const auto state = central.state;
 #if QT_IOS_PLATFORM_SDK_EQUAL_OR_ABOVE(__IPHONE_10_0) || QT_OSX_PLATFORM_SDK_EQUAL_OR_ABOVE(__MAC_10_13)
     if (state == CBManagerStatePoweredOn) {
@@ -243,18 +195,9 @@ QT_USE_NAMESPACE
             internalState = InquiryActive;
 
             if (inquiryTimeoutMS > 0) {
-                // We have a finite-length discovery, schedule stopScan,
-                // with a smaller time step, otherwise it can prevent
-                // 'self' from being deleted in time, which is not good
-                // (the block will retain 'self', waiting for timeout).
-                scanTimer.start();
-                const int timeChunkMS = std::min(timeStepMS, inquiryTimeoutMS);
-                dispatch_after(dispatch_time(DISPATCH_TIME_NOW,
-                                             int64_t(timeChunkMS / 1000. * NSEC_PER_SEC)),
-                                             leQueue,
-                                             ^{
-                                                   [self stopScan];
-                                              });
+                [elapsedTimer cancelTimer];
+                elapsedTimer.reset([[GCDTimerObjC alloc] initWithDelegate:self]);
+                [elapsedTimer startWithTimeout:inquiryTimeoutMS step:timeStepMS];
             }
 
             [manager scanForPeripheralsWithServices:nil options:nil];
@@ -284,19 +227,15 @@ QT_USE_NAMESPACE
         if (internalState == InquiryStarting) {
 #ifndef Q_OS_OSX
             // On iOS a user can see at this point an alert asking to
-            // enable Bluetooth in the "Settings" app. If a user does,
+            // enable Bluetooth in the "Settings" app. If a user does so,
             // we'll receive 'PoweredOn' state update later.
-            // No change in internalState. Wait for 30 seconds
-            // (we split it into smaller steps not to retain 'self' for
-            // too long ) ...
-            errorTimer.start();
-            dispatch_after(dispatch_time(DISPATCH_TIME_NOW,
-                                         (int64_t)(powerOffTimeStepS * NSEC_PER_SEC)),
-                                         leQueue,
-                                         ^{
-                                              [self handlePoweredOff];
-                                          });
+            // No change in internalState. Wait for 30 seconds.
+            [elapsedTimer cancelTimer];
+            elapsedTimer.reset([[GCDTimerObjC alloc] initWithDelegate:self]);
+            [elapsedTimer startWithTimeout:powerOffTimeoutMS step:300];
             return;
+#else
+            Q_UNUSED(powerOffTimeoutMS)
 #endif
             internalState = ErrorPoweredOff;
             emit notifier->CBManagerError(QBluetoothDeviceDiscoveryAgent::PoweredOffError);
@@ -318,6 +257,8 @@ QT_USE_NAMESPACE
         // lost; an update is imminent. "
         // Wait for this imminent update.
     }
+
+#pragma clang diagnostic pop
 }
 
 - (void)stop
@@ -325,6 +266,8 @@ QT_USE_NAMESPACE
     if (internalState == InquiryActive)
         [manager stopScan];
 
+    [elapsedTimer cancelTimer];
+
     [manager setDelegate:nil];
     internalState = InquiryCancelled;
 
diff --git a/src/bluetooth/osx/osxbtledeviceinquiry_p.h b/src/bluetooth/osx/osxbtledeviceinquiry_p.h
index fc787a6d..a19055ab 100644
--- a/src/bluetooth/osx/osxbtledeviceinquiry_p.h
+++ b/src/bluetooth/osx/osxbtledeviceinquiry_p.h
@@ -53,10 +53,10 @@
 
 #include "qbluetoothdevicediscoveryagent.h"
 #include "qbluetoothdeviceinfo.h"
+#include "osxbtgcdtimer_p.h"
 #include "osxbtutility_p.h"
 #include "osxbluetooth_p.h"
 
-#include <QtCore/qelapsedtimer.h>
 #include <QtCore/qglobal.h>
 #include <QtCore/qlist.h>
 
@@ -75,10 +75,8 @@ class LECBManagerNotifier;
 
 QT_END_NAMESPACE
 
-// Ugly but all these QT_PREPEND_NAMESPACE etc. are even worse ...
-using OSXBluetooth::LECBManagerNotifier;
-using OSXBluetooth::ObjCScopedPointer;
-using QT_PREPEND_NAMESPACE(QElapsedTimer);
+using QT_PREPEND_NAMESPACE(OSXBluetooth)::LECBManagerNotifier;
+using QT_PREPEND_NAMESPACE(OSXBluetooth)::ObjCScopedPointer;
 
 enum LEInquiryState
 {
@@ -90,7 +88,7 @@ enum LEInquiryState
     ErrorLENotSupported
 };
 
-@interface QT_MANGLE_NAMESPACE(OSXBTLEDeviceInquiry) : NSObject
+@interface QT_MANGLE_NAMESPACE(OSXBTLEDeviceInquiry) : NSObject<CBCentralManagerDelegate, QT_MANGLE_NAMESPACE(GCDTimerDelegate)>
 {
     LECBManagerNotifier *notifier;
     ObjCScopedPointer<CBCentralManager> manager;
@@ -99,16 +97,14 @@ enum LEInquiryState
     LEInquiryState internalState;
     int inquiryTimeoutMS;
 
-    // Timers to check if we can execute delayed callbacks:
-    QT_PREPEND_NAMESPACE(QElapsedTimer) errorTimer;
-    QT_PREPEND_NAMESPACE(QElapsedTimer) scanTimer;
+    QT_PREPEND_NAMESPACE(OSXBluetooth)::GCDTimer elapsedTimer;
 }
 
 - (id)initWithNotifier:(LECBManagerNotifier *)aNotifier;
 - (void)dealloc;
 
-// IMPORTANT: both 'startWithTimeout' and 'stop'
-// can be executed only on the "Qt's LE queue".
+// IMPORTANT: both 'startWithTimeout' and 'stop' MUST be executed on the "Qt's
+// LE queue".
 - (void)startWithTimeout:(int)timeout;
 - (void)stop;
 
diff --git a/src/bluetooth/osx/osxbtperipheralmanager.mm b/src/bluetooth/osx/osxbtperipheralmanager.mm
index 64c8cd90..d3d92f41 100644
--- a/src/bluetooth/osx/osxbtperipheralmanager.mm
+++ b/src/bluetooth/osx/osxbtperipheralmanager.mm
@@ -388,6 +388,9 @@ bool qt_validate_value_range(const QLowEnergyCharacteristicData &data)
 
 - (void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral
 {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunguarded-availability-new"
+
     if (peripheral != manager || !notifier)
         return;
 
@@ -436,6 +439,8 @@ bool qt_validate_value_range(const QLowEnergyCharacteristicData &data)
         emit notifier->LEnotSupported();
         state = PeripheralState::idle;
     }
+
+#pragma clang diagnostic pop
 }
 
 - (void)peripheralManager:(CBPeripheralManager *)peripheral