From eab4d274930f229c19d0652c652bfc9685fd531f Mon Sep 17 00:00:00 2001 From: David Lechner Date: Sat, 21 Mar 2020 11:09:56 -0500 Subject: [PATCH] Fix AccessDenied error on Windows BLE This fixes/works around an error that occurs when QLowEnergyService::discoverDetails is called from a QLowEnergyController::serviceDiscovered callback or a QLowEnergyController::discoveryFinished callback. It seems that ComPtr> deviceServices takes exclusive ownership of some operating system handle. When QLowEnergyService::discoverDetails is called, it calls deviceService3->GetIncludedServicesAsync(). This returns with status GattCommunicationStatus_AccessDenied and causes the error "Obtaining list of included services failed: 0" to be printed. By deferring emitting signals until later, the resource needed by deviceService3->GetIncludedServicesAsync() seems to be freed and the error is avoided. --- src/bluetooth/qlowenergycontroller_winrt_new.cpp | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/src/bluetooth/qlowenergycontroller_winrt_new.cpp b/src/bluetooth/qlowenergycontroller_winrt_new.cpp index f951d1a6..cee237d7 100644 --- a/src/bluetooth/qlowenergycontroller_winrt_new.cpp +++ b/src/bluetooth/qlowenergycontroller_winrt_new.cpp @@ -787,11 +787,22 @@ HRESULT QLowEnergyControllerPrivateWinRTNew::onServiceDiscoveryFinished(ABI::Win obtainIncludedServices(pointer, deviceService); - emit q->serviceDiscovered(service); + // If QLowEnergyService::discoverDetails is called from this callback, + // deviceService3->GetIncludedServicesAsync can fail with AccessDenied + // error. To work around this, we defer emitting the signal. + QTimer::singleShot(0, [q, service] () { + emit q->serviceDiscovered(service); + }); } setState(QLowEnergyController::DiscoveredState); - emit q->discoveryFinished(); + + // If QLowEnergyService::discoverDetails is called from this callback, + // deviceService3->GetIncludedServicesAsync can fail with AccessDenied + // error. To work around this, we defer emitting the signal. + QTimer::singleShot(0, [q] () { + emit q->discoveryFinished(); + }); return S_OK; } -- 2.25.1.windows.1