Replace calls to CoTaskMemFree via RAII wrapper

This change replaces all uses of task memory object that should be
freed with CoTaskMemFree (typically COM-related) with a wrapper class
that handles all memory deallocation and provides pointer semantic.

Change-Id: I73fe53eaa8ca37eb2ac6c6c05142e10e5a5615e9
Reviewed-by: Jøger Hansegård <joger.hansegard@qt.io>
Reviewed-by: Artem Dyomin <artem.dyomin@qt.io>
Reviewed-by: Lars Knoll <lars@knoll.priv.no>
(cherry picked from commit e988214e3e3f0e9f9005b8be1266a60255eef011)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

6 files changed, 137 insertions, 57 deletions

diff --git a/src/multimedia/windows/qcomtaskresource_p.h b/src/multimedia/windows/qcomtaskresource_p.h
index 7d3fd46ba..90554da5e 100644
--- a/src/multimedia/windows/qcomtaskresource_p.h
+++ b/src/multimedia/windows/qcomtaskresource_p.h
@@ -18,40 +18,135 @@
 #include <QtCore/qassert.h>
 
 #include <objbase.h>
+#include <algorithm>
+#include <type_traits>
 #include <utility>
 
-template<typename T>
-class QComTaskResource final
+class QEmptyDeleter final
 {
 public:
-    QComTaskResource() = default;
-    explicit QComTaskResource(T *resource) : m_resource(resource) { }
-    ~QComTaskResource() { reset(); }
+    template<typename T>
+    void operator()(T /*element*/) const
+    {
+    }
+};
 
-    QComTaskResource(const QComTaskResource<T> &source) = delete;
-    QComTaskResource &operator=(const QComTaskResource<T> &right) = delete;
+class QComDeleter final
+{
+public:
+    template<typename T>
+    void operator()(T element) const
+    {
+        element->Release();
+    }
+};
+
+template<typename T>
+class QComTaskResourceBase
+{
+public:
+    QComTaskResourceBase(const QComTaskResourceBase<T> &source) = delete;
+    QComTaskResourceBase &operator=(const QComTaskResourceBase<T> &right) = delete;
 
     explicit operator bool() const { return m_resource != nullptr; }
+
+    T *get() const { return m_resource; }
+
+protected:
+    QComTaskResourceBase() = default;
+    explicit QComTaskResourceBase(T *const resource) : m_resource(resource) { }
+
+    T *release() { return std::exchange(m_resource, nullptr); }
+
+    void reset(T *const resource = nullptr)
+    {
+        if (m_resource != resource) {
+            if (m_resource)
+                CoTaskMemFree(m_resource);
+            m_resource = resource;
+        }
+    }
+
+    T *m_resource = nullptr;
+};
+
+template<typename T, typename TElementDeleter = QEmptyDeleter>
+class QComTaskResource final : public QComTaskResourceBase<T>
+{
+    using Base = QComTaskResourceBase<T>;
+
+public:
+    using Base::QComTaskResourceBase;
+
+    ~QComTaskResource() { reset(); }
+
     T *operator->() const { return m_resource; }
+    T &operator*() const { return *m_resource; }
 
     T **address()
     {
         Q_ASSERT(m_resource == nullptr);
         return &m_resource;
     }
-    T *get() const { return m_resource; }
-    T *release() { return std::exchange(m_resource, nullptr); }
-    void reset(T *resource = nullptr)
+
+    using Base::release;
+    using Base::reset;
+
+private:
+    using Base::m_resource;
+};
+
+template<typename T, typename TElementDeleter>
+class QComTaskResource<T[], TElementDeleter> final : public QComTaskResourceBase<T>
+{
+    using Base = QComTaskResourceBase<T>;
+
+public:
+    QComTaskResource() = default;
+    explicit QComTaskResource(T *const resource, const std::size_t size)
+        : Base(resource), m_size(size)
+    {
+    }
+
+    ~QComTaskResource() { reset(); }
+
+    T &operator[](const std::size_t index) const
+    {
+        Q_ASSERT(index < m_size);
+        return m_resource[index];
+    }
+
+    T *release()
+    {
+        m_size = 0;
+
+        return Base::release();
+    }
+
+    void reset() { reset(nullptr, 0); }
+
+    void reset(T *const resource, const std::size_t size)
     {
         if (m_resource != resource) {
-            if (m_resource)
-                CoTaskMemFree(m_resource);
-            m_resource = resource;
+            resetElements();
+
+            Base::reset(resource);
+
+            m_size = size;
         }
     }
 
 private:
-    T *m_resource = nullptr;
+    void resetElements()
+    {
+        if constexpr (!std::is_same_v<TElementDeleter, QEmptyDeleter>) {
+            std::for_each(m_resource, m_resource + m_size, TElementDeleter());
+        }
+    }
+
+    std::size_t m_size = 0;
+
+    using Base::m_resource;
 };
 
 #endif
diff --git a/src/multimedia/windows/qwindowsaudiosink.cpp b/src/multimedia/windows/qwindowsaudiosink.cpp
index f585b83e2..1957d1cb6 100644
--- a/src/multimedia/windows/qwindowsaudiosink.cpp
+++ b/src/multimedia/windows/qwindowsaudiosink.cpp
@@ -15,6 +15,7 @@
 #include "qwindowsaudiosink_p.h"
 #include "qwindowsaudioutils_p.h"
 #include "qwindowsmultimediautils_p.h"
+#include "qcomtaskresource_p.h"
 
 #include <QtCore/QDataStream>
 #include <QtCore/qtimer.h>
@@ -215,8 +216,8 @@ bool QWindowsAudioSink::open()
 
     auto resetClient = qScopeGuard([this](){ m_audioClient.reset(); });
 
-    WAVEFORMATEX *pwfx = nullptr;
-    hr = m_audioClient->GetMixFormat(&pwfx);
+    QComTaskResource<WAVEFORMATEX> pwfx;
+    hr = m_audioClient->GetMixFormat(pwfx.address());
     if (FAILED(hr)) {
         qCWarning(qLcAudioOutput) << "Format unsupported" << errorString(hr);
         return false;
@@ -224,7 +225,6 @@ bool QWindowsAudioSink::open()
 
     if (!m_resampler.setup(m_format, QWindowsAudioUtils::waveFormatExToFormat(*pwfx))) {
         qCWarning(qLcAudioOutput) << "Failed to set up resampler";
-        CoTaskMemFree(pwfx);
         return false;
     }
 
@@ -233,15 +233,8 @@ bool QWindowsAudioSink::open()
 
     REFERENCE_TIME requestedDuration = m_format.durationForBytes(m_bufferSize) * 10;
 
-    hr = m_audioClient->Initialize(
-            AUDCLNT_SHAREMODE_SHARED,
-            0,
-            requestedDuration,
-            0,
-            pwfx,
-            nullptr);
-
-    CoTaskMemFree(pwfx);
+    hr = m_audioClient->Initialize(AUDCLNT_SHAREMODE_SHARED, 0, requestedDuration, 0, pwfx.get(),
+                                   nullptr);
 
     if (FAILED(hr)) {
         qCWarning(qLcAudioOutput) << "Failed to initialize audio client" << errorString(hr);
diff --git a/src/multimedia/windows/qwindowsaudiosource.cpp b/src/multimedia/windows/qwindowsaudiosource.cpp
index fa7a48705..01ac587fd 100644
--- a/src/multimedia/windows/qwindowsaudiosource.cpp
+++ b/src/multimedia/windows/qwindowsaudiosource.cpp
@@ -15,6 +15,7 @@
 
 #include "qwindowsaudiosource_p.h"
 #include "qwindowsmultimediautils_p.h"
+#include "qcomtaskresource_p.h"
 
 #include <QtCore/QDataStream>
 #include <QtCore/qtimer.h>
@@ -256,8 +257,8 @@ bool QWindowsAudioSource::open()
         return false;
     }
 
-    WAVEFORMATEX *pwfx = nullptr;
-    hr = m_audioClient->GetMixFormat(&pwfx);
+    QComTaskResource<WAVEFORMATEX> pwfx;
+    hr = m_audioClient->GetMixFormat(pwfx.address());
     if (FAILED(hr)) {
         qCWarning(qLcAudioSource) << "Format unsupported" << errorString(hr);
         return false;
@@ -265,7 +266,6 @@ bool QWindowsAudioSource::open()
 
     if (!m_resampler.setup(QWindowsAudioUtils::waveFormatExToFormat(*pwfx), m_format)) {
         qCWarning(qLcAudioSource) << "Failed to set up resampler";
-        CoTaskMemFree(pwfx);
         return false;
     }
 
@@ -274,9 +274,8 @@ bool QWindowsAudioSource::open()
 
     REFERENCE_TIME requestedDuration = m_format.durationForBytes(m_bufferSize);
 
-    hr = m_audioClient->Initialize(AUDCLNT_SHAREMODE_SHARED, 0, requestedDuration, 0, pwfx,
+    hr = m_audioClient->Initialize(AUDCLNT_SHAREMODE_SHARED, 0, requestedDuration, 0, pwfx.get(),
                                    nullptr);
-    CoTaskMemFree(pwfx);
 
     if (FAILED(hr)) {
         qCWarning(qLcAudioSource) << "Failed to initialize audio client" << errorString(hr);
diff --git a/src/multimedia/windows/qwindowsmediadevices.cpp b/src/multimedia/windows/qwindowsmediadevices.cpp
index c6c2b68df..bdb18b160 100644
--- a/src/multimedia/windows/qwindowsmediadevices.cpp
+++ b/src/multimedia/windows/qwindowsmediadevices.cpp
@@ -166,14 +166,12 @@ QWindowsMediaDevices::QWindowsMediaDevices()
             for (UINT i = 0; i < count; i++) {
                 QComPtr<IMMDevice> device;
                 DWORD state = 0;
-                LPWSTR id = nullptr;
+                QComTaskResource<WCHAR> id;
 
                 if (SUCCEEDED(devColl->Item(i, device.address()))
                     && SUCCEEDED(device->GetState(&state))
-                    && SUCCEEDED(device->GetId(&id)))
-                {
-                    devState.insert(QString::fromWCharArray(id), state);
-                    CoTaskMemFree(id);
+                    && SUCCEEDED(device->GetId(id.address()))) {
+                    devState.insert(QString::fromWCharArray(id.get()), state);
                 }
             }
         }
@@ -213,13 +211,12 @@ QList<QAudioDevice> QWindowsMediaDevices::availableDevices(QAudioDevice::Mode mo
     const auto defaultAudioDeviceID = [this, audioOut]{
         const auto dataFlow = audioOut ? EDataFlow::eRender : EDataFlow::eCapture;
         QComPtr<IMMDevice> dev;
-        LPWSTR id = nullptr;
+        QComTaskResource<WCHAR> id;
         QString sid;
 
         if (SUCCEEDED(m_deviceEnumerator->GetDefaultAudioEndpoint(dataFlow, ERole::eMultimedia, dev.address()))) {
-            if (dev && SUCCEEDED(dev->GetId(&id))) {
-                sid = QString::fromWCharArray(id);
-                CoTaskMemFree(id);
+            if (dev && SUCCEEDED(dev->GetId(id.address()))) {
+                sid = QString::fromWCharArray(id.get());
             }
         }
         return sid.toUtf8();
diff --git a/src/plugins/multimedia/windows/qwindowsformatinfo.cpp b/src/plugins/multimedia/windows/qwindowsformatinfo.cpp
index 28f89c97b..86c57632d 100644
--- a/src/plugins/multimedia/windows/qwindowsformatinfo.cpp
+++ b/src/plugins/multimedia/windows/qwindowsformatinfo.cpp
@@ -7,6 +7,7 @@
 #include <mftransform.h>
 #include <private/qcomptr_p.h>
 #include <private/qwindowsmultimediautils_p.h>
+#include <private/qcomtaskresource_p.h>
 
 #include <QtCore/qlist.h>
 #include <QtCore/qset.h>
@@ -33,12 +34,14 @@ template<typename T>
 static QSet<T> getCodecSet(GUID category)
 {
     QSet<T> codecSet;
-    IMFActivate **activateArray = nullptr;
+    IMFActivate **activateArrayRaw = nullptr;
     UINT32 num = 0;
 
-    HRESULT hr = MFTEnumEx(category, MFT_ENUM_FLAG_ALL, nullptr, nullptr, &activateArray, &num);
+    HRESULT hr = MFTEnumEx(category, MFT_ENUM_FLAG_ALL, nullptr, nullptr, &activateArrayRaw, &num);
 
     if (SUCCEEDED(hr)) {
+        QComTaskResource<IMFActivate *[], QComDeleter> activateArray(activateArrayRaw, num);
+
         for (UINT32 i = 0; i < num; ++i) {
             QComPtr<IMFTransform> transform;
             UINT32 typeIndex = 0;
@@ -61,11 +64,6 @@ static QSet<T> getCodecSet(GUID category)
                 }
             }
         }
-
-        for (UINT32 i = 0; i < num; ++i)
-            activateArray[i]->Release();
-
-        CoTaskMemFree(activateArray);
     }
 
     return codecSet;
diff --git a/src/plugins/multimedia/windows/qwindowsvideodevices.cpp b/src/plugins/multimedia/windows/qwindowsvideodevices.cpp
index 72a0312bc..5ce94fb8a 100644
--- a/src/plugins/multimedia/windows/qwindowsvideodevices.cpp
+++ b/src/plugins/multimedia/windows/qwindowsvideodevices.cpp
@@ -7,6 +7,7 @@
 #include <private/qwindowsmfdefs_p.h>
 #include <private/qwindowsmultimediautils_p.h>
 #include <private/qcomptr_p.h>
+#include <private/qcomtaskresource_p.h>
 
 #include <dbt.h>
 
@@ -132,13 +133,11 @@ static std::optional<QCameraFormat> createCameraFormat(IMFMediaType *mediaFormat
 
 static QString getString(IMFActivate *device, const IID &id)
 {
-    WCHAR *str = NULL;
+    QComTaskResource<WCHAR> str;
     UINT32 length = 0;
-    HRESULT hr = device->GetAllocatedString(id, &str, &length);
+    HRESULT hr = device->GetAllocatedString(id, str.address(), &length);
     if (SUCCEEDED(hr)) {
-        auto qstr = QString::fromWCharArray(str);
-        CoTaskMemFree(str);
-        return qstr;
+        return QString::fromWCharArray(str.get());
     } else {
         return {};
     }
@@ -186,20 +185,19 @@ static QList<QCameraDevice> readCameraDevices(IMFAttributes *attr)
 {
     QList<QCameraDevice> cameras;
     UINT32 count = 0;
-    IMFActivate **devices = NULL;
-    HRESULT hr = MFEnumDeviceSources(attr, &devices, &count);
+    IMFActivate **devicesRaw = nullptr;
+    HRESULT hr = MFEnumDeviceSources(attr, &devicesRaw, &count);
     if (SUCCEEDED(hr)) {
+        QComTaskResource<IMFActivate *[], QComDeleter> devices(devicesRaw, count);
+
         for (UINT32 i = 0; i < count; i++) {
             IMFActivate *device = devices[i];
             if (device) {
                 auto maybeCamera = createCameraDevice(device);
                 if (maybeCamera)
                     cameras << *maybeCamera;
-
-                device->Release();
             }
         }
-        CoTaskMemFree(devices);
     }
     return cameras;
 }