Fix memory leak in DirectWrite backend

This fixes a memory leak due to a missing call to release
on the localized names in populateFamilyAliases(). The
DirectWriteScope makes this automatic when it goes out
of scope.

We did release in the other places, but for hardening
the code a bit, this also adjusts them to use the scope
guard.

Change-Id: I88402fad930e36cdd3a78244941fb53ca214520e
Reviewed-by: Lars Knoll <lars@knoll.priv.no>

1 files changed, 24 insertions, 40 deletions

diff --git a/src/gui/text/windows/qwindowsdirectwritefontdatabase.cpp b/src/gui/text/windows/qwindowsdirectwritefontdatabase.cpp
index 499f43debb..ed6f1ae445 100644
--- a/src/gui/text/windows/qwindowsdirectwritefontdatabase.cpp
+++ b/src/gui/text/windows/qwindowsdirectwritefontdatabase.cpp
@@ -130,7 +130,7 @@ void QWindowsDirectWriteFontDatabase::populateFamily(const QString &familyName)
     const bool antialias = false;
     const int size = SMOOTH_SCALABLE;
 
-    IDWriteFontList *matchingFonts;
+    DirectWriteScope<IDWriteFontList> matchingFonts;
     if (SUCCEEDED(fontFamily->GetMatchingFonts(DWRITE_FONT_WEIGHT_REGULAR,
                                                DWRITE_FONT_STRETCH_NORMAL,
                                                DWRITE_FONT_STYLE_NORMAL,
@@ -138,7 +138,7 @@ void QWindowsDirectWriteFontDatabase::populateFamily(const QString &familyName)
         for (uint j = 0; j < matchingFonts->GetFontCount(); ++j) {
             IDWriteFont *font;
             if (SUCCEEDED(matchingFonts->GetFont(j, &font))) {
-                IDWriteFont1 *font1 = nullptr;
+                DirectWriteScope<IDWriteFont1> font1;
                 if (!SUCCEEDED(font->QueryInterface(__uuidof(IDWriteFont1),
                                                    reinterpret_cast<void **>(&font1)))) {
                     qCWarning(lcQpaFonts) << "COM object does not support IDWriteFont1";
@@ -148,27 +148,23 @@ void QWindowsDirectWriteFontDatabase::populateFamily(const QString &familyName)
                 QString defaultLocaleFamilyName;
                 QString englishLocaleFamilyName;
 
-                IDWriteFontFamily *fontFamily2;
+                DirectWriteScope<IDWriteFontFamily> fontFamily2;
                 if (SUCCEEDED(font1->GetFontFamily(&fontFamily2))) {
-                    IDWriteLocalizedStrings *names;
+                    DirectWriteScope<IDWriteLocalizedStrings> names;
                     if (SUCCEEDED(fontFamily2->GetFamilyNames(&names))) {
-                        defaultLocaleFamilyName = hasDefaultLocale ? localeString(names, defaultLocale) : QString();
-                        englishLocaleFamilyName = localeString(names, englishLocale);
-
-                        names->Release();
+                        defaultLocaleFamilyName = hasDefaultLocale ? localeString(*names, defaultLocale) : QString();
+                        englishLocaleFamilyName = localeString(*names, englishLocale);
                     }
-
-                    fontFamily2->Release();
                 }
 
                 if (defaultLocaleFamilyName.isEmpty() && englishLocaleFamilyName.isEmpty())
                     englishLocaleFamilyName = familyName;
 
                 {
-                    IDWriteLocalizedStrings *names;
+                    DirectWriteScope<IDWriteLocalizedStrings> names;
                     if (SUCCEEDED(font1->GetFaceNames(&names))) {
-                        QString defaultLocaleStyleName = hasDefaultLocale ? localeString(names, defaultLocale) : QString();
-                        QString englishLocaleStyleName = localeString(names, englishLocale);
+                        QString defaultLocaleStyleName = hasDefaultLocale ? localeString(*names, defaultLocale) : QString();
+                        QString englishLocaleStyleName = localeString(*names, englishLocale);
 
                         QFont::Stretch stretch = fromDirectWriteStretch(font1->GetStretch());
                         QFont::Style style = fromDirectWriteStyle(font1->GetStyle());
@@ -177,9 +173,9 @@ void QWindowsDirectWriteFontDatabase::populateFamily(const QString &familyName)
 
                         qCDebug(lcQpaFonts) << "Family" << familyName << "has english variant" << englishLocaleStyleName << ", in default locale:" << defaultLocaleStyleName << stretch << style << weight << fixed;
 
-                        IDWriteFontFace *face = nullptr;
+                        DirectWriteScope<IDWriteFontFace> face;
                         if (SUCCEEDED(font->CreateFontFace(&face))) {
-                            QSupportedWritingSystems writingSystems = supportedWritingSystems(face);
+                            QSupportedWritingSystems writingSystems = supportedWritingSystems(*face);
 
                             if (!englishLocaleStyleName.isEmpty() || defaultLocaleStyleName.isEmpty()) {
                                 qCDebug(lcQpaFonts) << "Font" << englishLocaleFamilyName << englishLocaleStyleName << "supports writing systems:" << writingSystems;
@@ -195,7 +191,7 @@ void QWindowsDirectWriteFontDatabase::populateFamily(const QString &familyName)
                                                                     size,
                                                                     fixed,
                                                                     writingSystems,
-                                                                    new FontHandle(face, englishLocaleFamilyName));
+                                                                    new FontHandle(*face, englishLocaleFamilyName));
                             }
 
                             if (!defaultLocaleFamilyName.isEmpty() && defaultLocaleFamilyName != englishLocaleFamilyName) {
@@ -210,22 +206,13 @@ void QWindowsDirectWriteFontDatabase::populateFamily(const QString &familyName)
                                                                     size,
                                                                     fixed,
                                                                     writingSystems,
-                                                                    new FontHandle(face, defaultLocaleFamilyName));
+                                                                    new FontHandle(*face, defaultLocaleFamilyName));
                             }
-
-                            face->Release();
                         }
-
-                        names->Release();
                     }
                 }
-
-                font1->Release();
-                font->Release();
             }
         }
-
-        matchingFonts->Release();
     }
 }
 
@@ -306,10 +293,10 @@ bool QWindowsDirectWriteFontDatabase::populateFamilyAliases(const QString &missi
                         DirectWriteScope<IDWriteFont1> font1;
                         if (SUCCEEDED(font->QueryInterface(__uuidof(IDWriteFont1),
                                                            reinterpret_cast<void **>(&font1)))) {
-                            IDWriteLocalizedStrings *names;
+                            DirectWriteScope<IDWriteLocalizedStrings> names;
                             if (SUCCEEDED(font1->GetFaceNames(&names))) {
                                 wchar_t englishLocale[] = L"en-us";
-                                QString englishLocaleStyleName = localeString(names, englishLocale);
+                                QString englishLocaleStyleName = localeString(*names, englishLocale);
 
                                 QFont::Stretch stretch = fromDirectWriteStretch(font1->GetStretch());
                                 QFont::Style style = fromDirectWriteStyle(font1->GetStyle());
@@ -747,47 +734,45 @@ void QWindowsDirectWriteFontDatabase::populateFontDatabase()
                                                     DWRITE_FONT_FAMILY_MODEL_TYPOGRAPHIC,
                                                     &fontCollection))) {
         for (uint i = 0; i < fontCollection->GetFontFamilyCount(); ++i) {
-            IDWriteFontFamily2 *fontFamily;
+            DirectWriteScope<IDWriteFontFamily2> fontFamily;
             if (SUCCEEDED(fontCollection->GetFontFamily(i, &fontFamily))) {
                 QString defaultLocaleName;
                 QString englishLocaleName;
 
-                IDWriteLocalizedStrings *names;
+                DirectWriteScope<IDWriteLocalizedStrings> names;
                 if (SUCCEEDED(fontFamily->GetFamilyNames(&names))) {
                     if (hasDefaultLocale)
-                        defaultLocaleName = localeString(names, defaultLocale);
+                        defaultLocaleName = localeString(*names, defaultLocale);
 
-                    englishLocaleName = localeString(names, englishLocale);
+                    englishLocaleName = localeString(*names, englishLocale);
                 }
 
                 qCDebug(lcQpaFonts) << "Registering font, english name = " << englishLocaleName << ", name in current locale = " << defaultLocaleName;
                 if (!defaultLocaleName.isEmpty()) {
                     registerFontFamily(defaultLocaleName);
-                    m_populatedFonts.insert(defaultLocaleName, fontFamily);
+                    m_populatedFonts.insert(defaultLocaleName, *fontFamily);
                     fontFamily->AddRef();
 
                     if (defaultLocaleName == defaultFontName && defaultFontName != systemDefaultFontName) {
                         qDebug(lcQpaFonts) << "Adding default font" << systemDefaultFontName << "as alternative to" << defaultLocaleName;
 
-                        m_populatedFonts.insert(systemDefaultFontName, fontFamily);
+                        m_populatedFonts.insert(systemDefaultFontName, *fontFamily);
                         fontFamily->AddRef();
                     }
                 }
 
                 if (!englishLocaleName.isEmpty() && englishLocaleName != defaultLocaleName) {
                     registerFontFamily(englishLocaleName);
-                    m_populatedFonts.insert(englishLocaleName, fontFamily);
+                    m_populatedFonts.insert(englishLocaleName, *fontFamily);
                     fontFamily->AddRef();
 
                     if (englishLocaleName == defaultFontName && defaultFontName != systemDefaultFontName) {
                         qDebug(lcQpaFonts) << "Adding default font" << systemDefaultFontName << "as alternative to" << englishLocaleName;
 
-                        m_populatedFonts.insert(systemDefaultFontName, fontFamily);
+                        m_populatedFonts.insert(systemDefaultFontName, *fontFamily);
                         fontFamily->AddRef();
                     }
                 }
-
-                fontFamily->Release();
             }
         }
     }
@@ -812,10 +797,9 @@ QFont QWindowsDirectWriteFontDatabase::defaultFont() const
 bool QWindowsDirectWriteFontDatabase::supportsVariableApplicationFonts() const
 {
     QSharedPointer<QWindowsFontEngineData> fontEngineData = data();
-    IDWriteFactory5 *factory5 = nullptr;
+    DirectWriteScope<IDWriteFactory5> factory5;
     if (SUCCEEDED(fontEngineData->directWriteFactory->QueryInterface(__uuidof(IDWriteFactory5),
                                                                      reinterpret_cast<void **>(&factory5)))) {
-        factory5->Release();
         return true;
     }