gecko-dev/widget/InProcessCompositorWidget.h
Brad Werth f963cdd26f Bug 1674142: Add additional checks to find a crash in InProcessCompositorWidget::PreRender. r=jrmuizel
There are decreasingly-plausible explanations for how mWidget becomes  NULL in
the crash reports we are seeing. This patch closes one of the possible -- but
still unlikely -- reasons by checking for a NULL pointer after a static_cast.
The contract for static_cast should not allow it to return NULL with non-NULL
input, but it would trigger the crashes we are seeing.

Another possibility is that dangling pointers to InProcessCompositorWidget
objects are being held. The patch adds a canary pointer and a sanity-checking
function that's called in all member functions that dereference mWidget.

Differential Revision: https://phabricator.services.mozilla.com/D106672
2021-03-10 00:45:49 +00:00

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2.1 KiB
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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_widget_InProcessCompositorWidget_h__
#define mozilla_widget_InProcessCompositorWidget_h__
#include "CompositorWidget.h"
namespace mozilla {
namespace widget {
// This version of CompositorWidget implements a wrapper around
// nsBaseWidget.
class InProcessCompositorWidget : public CompositorWidget {
public:
explicit InProcessCompositorWidget(const layers::CompositorOptions& aOptions,
nsBaseWidget* aWidget);
virtual bool PreRender(WidgetRenderingContext* aManager) override;
virtual void PostRender(WidgetRenderingContext* aManager) override;
virtual RefPtr<layers::NativeLayerRoot> GetNativeLayerRoot() override;
virtual already_AddRefed<gfx::DrawTarget> StartRemoteDrawing() override;
virtual already_AddRefed<gfx::DrawTarget> StartRemoteDrawingInRegion(
const LayoutDeviceIntRegion& aInvalidRegion,
layers::BufferMode* aBufferMode) override;
virtual void EndRemoteDrawing() override;
virtual void EndRemoteDrawingInRegion(
gfx::DrawTarget* aDrawTarget,
const LayoutDeviceIntRegion& aInvalidRegion) override;
virtual void CleanupRemoteDrawing() override;
virtual void CleanupWindowEffects() override;
virtual bool InitCompositor(layers::Compositor* aCompositor) override;
virtual LayoutDeviceIntSize GetClientSize() override;
virtual uint32_t GetGLFrameBufferFormat() override;
virtual void ObserveVsync(VsyncObserver* aObserver) override;
virtual uintptr_t GetWidgetKey() override;
// If you can override this method, inherit from CompositorWidget instead.
nsIWidget* RealWidget() override;
protected:
nsBaseWidget* mWidget;
// Bug 1679368: Maintain an additional widget pointer, constant, and
// function for sanity checking while we chase a crash.
static const char* CANARY_VALUE;
const char* mCanary;
nsBaseWidget* mWidgetSanity;
void CheckWidgetSanity();
};
} // namespace widget
} // namespace mozilla
#endif