Bug 1362117 - keep NativeFontResourceFontconfig alive while its associated cairo_font_face_t is alive. r=jrmuizel

MozReview-Commit-ID: HxeOQPTP6WL

gfx/2d/NativeFontResourceFontconfig.cpp

@@ -53,7 +53,7 @@ already_AddRefed<UnscaledFont>
 NativeFontResourceFontconfig::CreateUnscaledFont(uint32_t aIndex,
                                                  const uint8_t* aInstanceData, uint32_t aInstanceDataLength)
 {
-  RefPtr<UnscaledFont> unscaledFont = new UnscaledFontFontconfig(mFace);
+  RefPtr<UnscaledFont> unscaledFont = new UnscaledFontFontconfig(mFace, this);
   return unscaledFont.forget();
 }
 

gfx/2d/ScaledFontFontconfig.cpp

@@ -242,13 +242,23 @@ UnscaledFontFontconfig::CreateScaledFont(Float aGlyphSize,
   }
   const ScaledFontFontconfig::InstanceData *instanceData =
     reinterpret_cast<const ScaledFontFontconfig::InstanceData*>(aInstanceData);
-  return ScaledFontFontconfig::CreateFromInstanceData(*instanceData, this, aGlyphSize);
+  return ScaledFontFontconfig::CreateFromInstanceData(*instanceData, this, aGlyphSize,
+                                                      mNativeFontResource.get());
+}
+
+static cairo_user_data_key_t sNativeFontResourceKey;
+
+static void
+ReleaseNativeFontResource(void* aData)
+{
+  static_cast<NativeFontResource*>(aData)->Release();
 }
 
 already_AddRefed<ScaledFont>
 ScaledFontFontconfig::CreateFromInstanceData(const InstanceData& aInstanceData,
                                              UnscaledFontFontconfig* aUnscaledFont,
-                                             Float aSize)
+                                             Float aSize,
+                                             NativeFontResource* aNativeFontResource)
 {
   FcPattern* pattern = FcPatternCreate();
   if (!pattern) {
@@ -271,6 +281,22 @@ ScaledFontFontconfig::CreateFromInstanceData(const InstanceData& aInstanceData,
     return nullptr;
   }
 
+  if (aNativeFontResource) {
+    // Bug 1362117 - Cairo may keep the font face alive after the owning NativeFontResource
+    // was freed. To prevent this, we must bind the NativeFontResource to the font face so that
+    // it stays alive at least as long as the font face.
+    if (cairo_font_face_set_user_data(font,
+                                      &sNativeFontResourceKey,
+                                      aNativeFontResource,
+                                      ReleaseNativeFontResource) != CAIRO_STATUS_SUCCESS) {
+      gfxWarning() << "Failed binding NativeFontResource to Cairo font face";
+      cairo_font_face_destroy(font);
+      FcPatternDestroy(pattern);
+      return nullptr;
+    }
+    aNativeFontResource->AddRef();
+  }
+
   cairo_matrix_t sizeMatrix;
   aInstanceData.SetupFontMatrix(&sizeMatrix);
 

gfx/2d/ScaledFontFontconfig.h

@@ -66,7 +66,8 @@ private:
   static already_AddRefed<ScaledFont>
     CreateFromInstanceData(const InstanceData& aInstanceData,
                            UnscaledFontFontconfig* aUnscaledFont,
-                           Float aSize);
+                           Float aSize,
+                           NativeFontResource* aNativeFontResource = nullptr);
 
   FcPattern* mPattern;
 };

gfx/2d/UnscaledFontFreeType.h

@@ -73,6 +73,11 @@ public:
                                   uint32_t aIndex = 0)
     : UnscaledFontFreeType(aFile, aIndex)
   {}
+  UnscaledFontFontconfig(FT_Face aFace,
+                         NativeFontResource* aNativeFontResource)
+    : UnscaledFontFreeType(aFace, false)
+    , mNativeFontResource(aNativeFontResource)
+  {}
 
   FontType GetType() const override { return FontType::FONTCONFIG; }
 
@@ -83,6 +88,9 @@ public:
     CreateScaledFont(Float aGlyphSize,
                      const uint8_t* aInstanceData,
                      uint32_t aInstanceDataLength) override;
+
+private:
+  RefPtr<NativeFontResource> mNativeFontResource;
 };
 #endif