Clear previous bluetooth device/service discovery errors on restart

An example of the problem is when discovery is first tried while
bluetooth is OFF, and one gets the corresponding error. Then the
bluetooth is switched ON, and the discovery is restarted successfully.
However in this case the error() still remains as "power OFF" error
instead of "no error", which is misleading.

With device discovery agent the clearing is done at each individual
backend, rather than at the common public class start(). This is due
to the pending cancel/start logic, which we probably shouldn't interfere
with by clearing errors amidst pending operation. The Darwin backend
already cleared the error in its start(), and with this commit the
intent is to add similar clearing to the Android/Bluez/Win.

Pick-to: 6.2 6.3 6.4
Fixes: QTBUG-104473
Change-Id: I713590a26eb2b8d4ee7873f3fe84e63e504523df
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>

8 files changed, 44 insertions, 1 deletions

diff --git a/src/bluetooth/qbluetoothdevicediscoveryagent.cpp b/src/bluetooth/qbluetoothdevicediscoveryagent.cpp
index 5dae7f2f..da88f4aa 100644
--- a/src/bluetooth/qbluetoothdevicediscoveryagent.cpp
+++ b/src/bluetooth/qbluetoothdevicediscoveryagent.cpp
@@ -349,6 +349,8 @@ bool QBluetoothDeviceDiscoveryAgent::isActive() const
 
 /*!
     Returns the last error.
+
+    Any possible previous errors are cleared upon restarting the discovery.
 */
 QBluetoothDeviceDiscoveryAgent::Error QBluetoothDeviceDiscoveryAgent::error() const
 {
@@ -359,6 +361,8 @@ QBluetoothDeviceDiscoveryAgent::Error QBluetoothDeviceDiscoveryAgent::error() co
 
 /*!
     Returns a human-readable description of the last error.
+
+    \sa error(), errorOccurred()
 */
 QString QBluetoothDeviceDiscoveryAgent::errorString() const
 {
diff --git a/src/bluetooth/qbluetoothdevicediscoveryagent_android.cpp b/src/bluetooth/qbluetoothdevicediscoveryagent_android.cpp
index cd6327f5..b52313e0 100644
--- a/src/bluetooth/qbluetoothdevicediscoveryagent_android.cpp
+++ b/src/bluetooth/qbluetoothdevicediscoveryagent_android.cpp
@@ -205,6 +205,8 @@ void QBluetoothDeviceDiscoveryAgentPrivate::start(QBluetoothDeviceDiscoveryAgent
         QObject::connect(receiver, SIGNAL(finished()), this, SLOT(processSdpDiscoveryFinished()));
     }
 
+    lastError = QBluetoothDeviceDiscoveryAgent::NoError;
+    errorString.clear();
     discoveredDevices.clear();
 
     // by arbitrary definition we run classic search first
diff --git a/src/bluetooth/qbluetoothdevicediscoveryagent_bluez.cpp b/src/bluetooth/qbluetoothdevicediscoveryagent_bluez.cpp
index b93dde22..24ae2511 100644
--- a/src/bluetooth/qbluetoothdevicediscoveryagent_bluez.cpp
+++ b/src/bluetooth/qbluetoothdevicediscoveryagent_bluez.cpp
@@ -76,6 +76,8 @@ void QBluetoothDeviceDiscoveryAgentPrivate::start(QBluetoothDeviceDiscoveryAgent
         return;
     }
 
+    lastError = QBluetoothDeviceDiscoveryAgent::NoError;
+    errorString.clear();
     discoveredDevices.clear();
     devicesProperties.clear();
 
diff --git a/src/bluetooth/qbluetoothdevicediscoveryagent_winrt.cpp b/src/bluetooth/qbluetoothdevicediscoveryagent_winrt.cpp
index 37659d4b..8940a2c0 100644
--- a/src/bluetooth/qbluetoothdevicediscoveryagent_winrt.cpp
+++ b/src/bluetooth/qbluetoothdevicediscoveryagent_winrt.cpp
@@ -765,6 +765,8 @@ void QBluetoothDeviceDiscoveryAgentPrivate::start(QBluetoothDeviceDiscoveryAgent
 
     worker = std::make_shared<QWinRTBluetoothDeviceDiscoveryWorker>(methods,
                                                                     lowEnergySearchTimeout);
+    lastError = QBluetoothDeviceDiscoveryAgent::NoError;
+    errorString.clear();
     discoveredDevices.clear();
     connect(worker.get(), &QWinRTBluetoothDeviceDiscoveryWorker::deviceFound,
             this, &QBluetoothDeviceDiscoveryAgentPrivate::registerDevice);
diff --git a/src/bluetooth/qbluetoothservicediscoveryagent.cpp b/src/bluetooth/qbluetoothservicediscoveryagent.cpp
index 8456c341..2f5d9dd6 100644
--- a/src/bluetooth/qbluetoothservicediscoveryagent.cpp
+++ b/src/bluetooth/qbluetoothservicediscoveryagent.cpp
@@ -308,6 +308,9 @@ void QBluetoothServiceDiscoveryAgent::start(DiscoveryMode mode)
         d->foundHostAdapterPath.clear();
 #endif
         d->setDiscoveryMode(mode);
+        // Clear any possible previous errors
+        d->error = QBluetoothServiceDiscoveryAgent::NoError;
+        d->errorString.clear();
         if (d->deviceAddress.isNull()) {
             d->startDeviceDiscovery();
         } else {
@@ -378,9 +381,10 @@ bool QBluetoothServiceDiscoveryAgent::isActive() const
     discovered by a scan, errors during service discovery on individual
     devices are not saved and no signals are emitted. In this case, errors are
     fairly normal as some devices may not respond to discovery or
-    may no longer be in range.  Such errors are surpressed.  If no services
+    may no longer be in range.  Such errors are suppressed.  If no services
     are returned, it can be assumed no services could be discovered.
 
+    Any possible previous errors are cleared upon restarting the discovery.
 */
 QBluetoothServiceDiscoveryAgent::Error QBluetoothServiceDiscoveryAgent::error() const
 {
@@ -392,6 +396,8 @@ QBluetoothServiceDiscoveryAgent::Error QBluetoothServiceDiscoveryAgent::error()
 /*!
     Returns a human-readable description of the last error that occurred during the
     service discovery.
+
+    \sa error(), errorOccurred()
 */
 QString QBluetoothServiceDiscoveryAgent::errorString() const
 {
diff --git a/tests/bttestui/btlocaldevice.cpp b/tests/bttestui/btlocaldevice.cpp
index e6aa8a8e..bf8f492e 100644
--- a/tests/bttestui/btlocaldevice.cpp
+++ b/tests/bttestui/btlocaldevice.cpp
@@ -794,6 +794,27 @@ void BtLocalDevice::dumpServerInformation()
     }
 }
 
+template <typename T>
+void printError(const QLatin1StringView name, T* ptr)
+{
+    if (!ptr)
+        return;
+    qDebug() << name << "error:" << ptr->error();
+}
+
+void BtLocalDevice::dumpErrors()
+{
+    qDebug() << "###### Errors";
+    printError("Device agent"_L1, deviceAgent);
+    printError("Service agent"_L1, serviceAgent);
+    printError("LE Central"_L1, leCentralController.get());
+    printError("LE Central Service"_L1, leCentralService.get());
+    printError("LE Peripheral"_L1, lePeripheralController.get());
+    printError("LE Peripheral Service"_L1, lePeripheralService.get());
+    printError("Socket"_L1, socket);
+    printError("Server"_L1, server);
+}
+
 void BtLocalDevice::dumpInformation()
 {
     if (!localDevice)
diff --git a/tests/bttestui/btlocaldevice.h b/tests/bttestui/btlocaldevice.h
index 97e64ed1..4c093bdb 100644
--- a/tests/bttestui/btlocaldevice.h
+++ b/tests/bttestui/btlocaldevice.h
@@ -50,6 +50,7 @@ signals:
 public slots:
     //QBluetoothLocalDevice
     void dumpInformation();
+    void dumpErrors();
     void powerOn();
     void reset();
     void setHostMode(int newMode);
diff --git a/tests/bttestui/main.qml b/tests/bttestui/main.qml
index f0510fcf..38823199 100644
--- a/tests/bttestui/main.qml
+++ b/tests/bttestui/main.qml
@@ -350,6 +350,11 @@ Flickable {
                     buttonText: "Reset"
                     onClicked: device.reset()
                 }
+                Button {
+                    id: errorButton
+                    buttonText: "Errors"
+                    onClicked: device.dumpErrors()
+                }
             }
         }
     }